The figures of the early stages of a minute ichneumon represented on the same plate (Fig. 7, larva, and 7a, pupa, of Anthophorabia megachilis) which is parasitic on Megachile, the Leaf-cutter bee, illustrates the transformations of the Ichneumon flies, the smallest species of which yet known (and we believe the smallest insect known at all) is the Pteratomus Putnami (Pl. I, Fig. 8, wanting the hind leg), or "winged atom," which is only one-ninetieth of an inch in length, and is parasitic on Anthophorabia, itself a parasite. A species of mite (Plate I, Figs. 9; 9a, the same seen from beneath) is always to be found In humble bees' nests, but it is not thought to be specially obnoxious to the bees themselves, though several species of mites (Gamasus, etc.) are known to be parasitic on insects.
A FEW WORDS ABOUT MOTHS.
The butterflies and moths from their beauty and grace, have always been the favorites among amateur entomologists, and rare and costly works have been published in which their forms and gorgeous colors are represented in the best style of natural history art. We need only mention the folio volume of Madam Merian of the last century, Harris's Aurelian, the works of Cramer, Stoll, Drury, Huebner, Horsfield, Doubleday and Westwood, and Hewitson, as comprising the most luxurious and costly entomological works.
Near the close of the last century, John Abbot went from London and spent several years in Georgia, rearing the larger and more showy butterflies and moths, and painting them in the larva, chrysalis and adult, or imago stage. These drawings he sent to London to be sold. Many of them were collected by Sir James Edward Smith, and published under the title of "The Natural History of the Rarer Lepidopterous Insects of Georgia, collected from the Observations of John Abbot, with the Plants on which they Feed." (London, 1797. 2 vols., fol.) Besides these two rare volumes there are sixteen folio volumes of drawings by Abbot in the Library of the British Museum. This work is of especial interest to the American student as it illustrates the early stages of many of our butterflies and moths.
Indeed the study of insects possesses most of its interest when we observe their habits and transformations. Caterpillars are always to be found, and with a little practice are easy to raise; we would therefore advise any one desirous of beginning the study of insects to take up the butterflies and moths. They are perhaps easier to study than any other group of insects, and are more ornamental in the cabinet. As a scientific study we would recommend it to ladies as next to botany in interest and in the ease in which specimens may be collected and examined. The example of Madam Merian, and several ladies in this country who have greatly aided science by their well filled cabinets, and critical knowledge of the various species and their transformations, is an earnest of what may be expected from their followers. Though the moths are easy to study compared with the bees, flies, beetles and bugs, and dragon flies, yet many questions of great interest in philosophical entomology have been answered by our knowledge of their structure and mode of growth. The great works of Herold on the evolution of a caterpillar; of Lyonet on the anatomy of the Cossus; of Newport on that of the Sphinx; and of Siebold on the parthenogenesis of insects, are proofs that the moths have engaged the attention of some of the master minds in science.
The study of the transformations of the moths is also of great importance to one who would acquaint himself with the questions concerning the growth and metamorphoses and origin of animals. We should remember that the very words "metamorphosis" and "transformation," now so generally applied to other groups of animals and used in philosophical botany, were first suggested by those who observed that the moth and butterfly attain their maturity only by passing through wonderful changes of form and modes of life.
The knowledge of the fact that all animals pass through some sort of a metamorphosis is very recent in physiology. Moreover the fact that these morphological eras in the life of an individual animal accord most unerringly with the gradation of forms in the type of which it is a member, was the discovery of the eminent physiologist Von Baer. Up to this time the true significance of the luxuriance and diversity of larval forms had never seriously engaged the attention of systematists in entomology.
What can possibly be the meaning of all this putting on and taking off of caterpillar habiliments, or in other words, the process of moulting, with the frequent changes in ornamentation, and the seeming fastidiousness and queer fancies and strange conceits of these young and giddy insects seems hidden and mysterious to human observation. Indeed, few care to spend the time and trouble necessary to observe the insect through its transformations; and that done, if only the larva of the perfect insect can be identified and its form sketched how much was gained! A truthful and circumstantial biography, in all its relations, of a single insect has yet to be written!
We should also apply our knowledge of the larval forms of insects to the details of their classification into families and genera, constantly collating our knowledge of the early stages with the structural relations that accompany them in the perfect state.
The simple form of the caterpillar seems to be a concentration of the characters of the perfect insect, and presents easy characters by which to distinguish the minor groups; and the relative rank of the higher divisions will only be definitely settled when their forms and methods of transformation are thoroughly known. Thus, for example, in two groups of the large Attacus-like moths, which are so amply illustrated in Dr. Harris's "Treatise on Insects injurious to Vegetation"; if we take the different forms of the caterpillars of the Tau moth of Europe, which are figured by Duponchel and Godard, we find that the very young larva has four horn-like processes on the front, and four on the back part of the body. The full grown larva of the Regalis moth, of the Southern and Middle states, is very similarly ornamented. It is an embryonic form, and therefore inferior in rank to the Tau moth. Multiply these horns over the surface of the body, lessen their size, and crown them with hairs, and we have our Io moth, so destructive to corn. Now take off the hairs, elongating and thinning out the tubercles, and make up the loss by the increased size of the worm, and we have the caterpillar of our common Cecropia moth. Again, remove the naked tubercles almost wholly, smooth off the surface of the body, and contract its length, thus giving a greater convexity and angularity to the rings, and we have before us the larva of the stately Luna moth that tops this royal family. Here are certain criteria for placing these insects before our minds in the order that nature has placed them. We have certain facts for determining which of these three insects is highest and which lowest in the scale, when we see the larva of the Luna moth throwing off successively the Io and Cecropia forms to take on its own higher features. So that there is a meaning in all this shifting of insect toggery.
This is but an example of the many ways in which both pleasure and mental profit may be realized from the thoughtful study of caterpillar life.
In collecting butterflies and moths for cabinet specimens, one needs a gauze net a foot and a half deep, with the wire frame a foot in diameter; a wide-mouthed bottle containing a parcel of cyanide of potassium gummed on the side, in which to kill the moths, which should, as soon as life is extinct, be pinned in a cork-lined collecting box carried in the coat pocket. The captures should then be spread and dried on a grooved setting board, and a cabinet formed of cork-lined boxes or drawers; as a substitute for cork, frames with paper tightly stretched over them may be used, or the pith of corn-stalks or palm wood. Caterpillars should be preserved in spirits, or in glycerine with a little alcohol added.
Some persons ingeniously empty the skins and inflate them over a flame so that they may be pinned by the side of the adult.
Some of the most troublesome and noxious insects are found among the moths. I need only mention the canker worm and American tent caterpillar, and the various kinds of cut worms, as instances.
We must not, however, forget the good done by insects. They undoubtedly tend by their attacks to prevent an undue growth of vegetation. The pruning done to a tree or herb by certain insects undoubtedly causes a more healthy growth of the branches and leaves, and ultimately a greater production fruit. Again, as pollen-bearers, insects are a most powerful agency in nature. It is undoubtedly the fact that the presence, of bees in orchards increases the fruit crop, and thus the thousands of moths (though injurious as caterpillars), wild bees and other insects, that seem to live without purpose, are really, though few realize it, among the best friends and allies of man.
Moreover, insects are of great use as scavengers; such are the young or maggots of the house fly, the mosquitoes, and numerous other forms, that seem created only to vex us when in the winged state. Still a larger proportion of insects are directly beneficial from their habit of attacking injurious species, such as the ichneumons (Fig. 43, the ichneumon of the American silk worm) and certain flies (Fig. 44, Tachina); also many carnivorous species of wasps beetles and flies, dragon flies and Aphis lions (Fig. 45, the lace-winged fly; adult, larva and eggs).
But few, however, suspect how enormous are the losses to crops in this country entailed by the attacks of the injurious species. In Europe, the subject of applied entomology has always attracted a great deal of attention. Most sumptuous works, elegant quartos prepared by naturalists known the world over, and published at government expense, together with smaller treatises, have frequently appeared; while the subject is taught in the numerous agricultural colleges and schools, especially of Germany.
In the densely populated countries of Europe, the losses occasioned by injurious insects are most severely felt, though from many causes, such as the greater abundance of their insect parasites, and the far greater care taken by the people to exterminate their insect enemies, they have not proved so destructive as in our own land.
In this connection I may quote from one of Dr. Asa Fitch's reports on the noxious insects of New York, where he says: "I find that in our wheat-fields here, the midge formed 59 per cent. of all the insects on this grain the past summer; whilst in France, the preceding summer, only 7 per cent. of the insects on wheat were of this species. In France the parasitic destroyers amounted to 85 per cent.; while in this country our parasites form only 10 per cent."
"A true knowledge of practical entomology may well be said to be in its infancy in our own country, when, as is well-known to agriculturists, the cultivation of wheat has almost been given up in New England, New York, Pennsylvania, Ohio and Virginia, from the attacks of the wheat midge, Hessian fly, joint worm, and chinch bug. According to Dr. Shimer's estimate, says Mr. Riley, in his Second Annual Report on the Injurious Insects of Missouri, which may be considered a reasonable one, in the year 1864 three-fourths of the wheat, and one-half of the corn crop were destroyed by the chinch bug throughout many extensive districts, comprising almost the entire North-West. At the annual rate of increase, according to the United States Census, in the State of Illinois, the wheat crop ought to have been about thirty millions of bushels, and the corn crop about one hundred and thirty-eight million bushels. Putting the cash value of wheat at $1.25, and that of corn at 50 cents, the cash value of the corn and wheat destroyed by this insignificant little bug, no bigger than a grain of rice, in one single State and one single year, will therefore, according to the above figures, foot up to the astounding total of over seventy-three millions of dollars!"
The imported cabbage butterfly (Pieris rapae), recently introduced from Europe, is estimated by the Abbe Provatncher, a Canadian entomologist, to destroy annually two hundred and forty thousand dollars' worth of cabbages around Quebec. The Hessian fly, according to Dr. Fitch, destroyed fifteen million dollars' worth of wheat in New York State in one year (1854). The army worm of the North (Leucania unipuncta), which was so abundant in 1861, from New England to Kansas, was reported to have done damage that year in Eastern Massachusetts exceeding half a million of dollars. The joint worm (Isosoma hordei) alone sometimes cuts off whole fields of grain in Virginia and northward. The Colorado potato beetle is steadily moving eastward, now ravaging the fields in Indiana and Ohio, and only the forethought and ingenuity in devising means of checking its attacks, resulting from a thorough study of its habits, will deliver our wasted fields from its direful assaults.
These are the injuries done by the more abundant kinds of insects injurious to crops. We should not forget that each fruit or shade tree, garden shrub or vegetable, has a host of insects peculiar to it, and which, year after year, renew their attacks. I could enumerate upwards of fifty species of insects which prey upon cereals and grass, and as many which infest our field crops. Some thirty well known species ravage our garden vegetables. There are nearly fifty species which attack the grape vine, and their number is rapidly increasing. About seventy-five species make their annual onset upon the apple tree, and nearly an equal number may be found upon the plum, pear, peach and cherry. Among our shade trees, over fifty species infest the oak; twenty-five the elm; seventy-five the walnut, and over one hundred species of insects prey upon the pine.
Indeed, we may reasonably calculate the annual loss in our country alone, from noxious animals and the lower forms of plants, such as rust, smut and mildew, as (at a low estimate) not far from five hundred million dollars annually. Of this amount, at least one-tenth, or fifty million dollars, could probably be saved by human exertions.
To save a portion of this annual loss of food stuffs, fruits and lumber, should be the first object of farmers and gardeners. When this saving is made, farming will become a profitable and safe profession. But while a few are well informed as to the losses sustained by injurious insects, and use means to ward off their attacks, their efforts are constantly foiled by the negligence of their neighbors. As illustrated so well by the history of the incursions of the army worm and canker worm, it is only by a combination between farmers and orchardists that these and other pests can be kept under. The matter can be best reached by legislation. We have fish and game laws; why should we not have an insect law? Why should we not frame a law providing that farmers, and all owning a garden or orchard, should cooperate in taking preventive measures against injurious insects, such as early or late planting of cereals, to avert the attacks of the wheat midge and Hessian fly; the burning of stubble in the autumn and spring to destroy the joint worm; the combined use of proper remedies against the canker worm, the various cut worms, and other noxious caterpillars? A law carried out by a proper State entomological constabulary, if it may be so designated, would compel the idle and shiftless to clear their farms and gardens of noxious animals.
Among some of the injurious insects reported on by Mr. Riley, the State Entomologist of Missouri, is a new pest to the cucumber in the West, the Pickle worm (Phacellura nitidalis, Fig. 46). This is a caterpillar which bores into the cucumbers when large enough to pickle, and which is occasionally found in pickles. Three or four worms sometimes occur in a cucumber, and in the garden a single one will cause it to rot. One of the most troublesome intruders in our graperies is the Vine dresser (Choerocampa pampinatrix, Fig. 47, larva and pupa; Fig. 48, adult), a single caterpillar of which will sometimes "strip a small vine of its leaves in a few nights," and occasionally nips off bunches of half-grown grapes.
Another caterpillar, which is sometimes so abundant as nearly to defoliate the grape vine, is the eight spotted Alypia (Fig. 49; a, larva; b, side view of a segment). This must not be confounded with the bluish larva of the Wood Nymph, Eudryas grata (Fig. 50), which differs from the Alypia caterpillar in being bluish, and in wanting the white patches on the side of the body, and the more prominent hump on the end of the body. Another moth (Psychomorpha epimenis, Fig. 51, a, larva; b, side view of a segment; c, top view of the hump), also feeds on the grape, eating the terminal buds. It is also bluish, and wants the orange bands on the side of the body. Another moth of this family is the American Procris (Acoloithus Americana, Fig. 52a, larva; b, pupa; c, cocoon; d, e, imago); a dark blue moth, with a deep orange collar, whose black and yellow caterpillar is gregarious (Fig. 53), living in companies of a dozen or more and eating the softer parts of the leaves. It is quite common in the Western and Southern States. The figure represents two separate broods of caterpillars feeding on either side of the midrib of the leaf. But if the moths are, as a rule, the enemies of our crops, there are the silk worms of the East and Southern Europe and California, which afford the means of support to multitudes of the poorer classes, and supply one of the most valuable articles of clothing. Blot out the silk worm, and we should remove one of the most important sources of national wealth, the annual revenue from the silk trade of the world amounting to $254,500,000.
Silk culture is rapidly assuming importance in California, and though the Chinese silk worm has not been successfully cultivated in the Eastern States, yet the American silk worm, Teleas Polyphemus (see frontispiece, male; Fig. 54, larva; 55, pupa; 56, cocoon), can, we are assured by Mr. Trouvelot, be made a source of profit.
This is a splendid member of the group of which the gigantic Attacus Atlas of China is a type. It is a large, fawn colored moth with a tawny tinge; the caterpillar is pale green, and is of the size indicated in the cut. Mr. Trouvelot says that of the several kinds of silk worms, the larva of the present species alone deserves attention. The cocoons of Platysamia Cecropia may be rendered of some commercial value, as the silk can be carded, but the chief objection is the difficulty of raising the larva.
"The Polyphemus worm spins a strong, dense, oval cocoon, which is closed at each end, while the silk has a very strong and glossy fibre." Mr. Trouvelot, from whose interesting account in the first volume of the "American Naturalist" we quote, says that in 1865 "not less than a million could be seen feeding in the open air upon bushes covered with a net; five acres of woodland were swarming with caterpillar life." The bushes were scrub oaks, the worms being protected by a net. After meeting with such great success Mr. Trouvelot lost all his worms by pebrine, the germs being imported in eggs received from Japan through M. Guerin-Meneville of Paris. Enough, however, was done to prove that silk raising can be carried on profitably, when due precautions are taken, as far north as Boston. As this moth extends to the tropics, it can be reared with greater facility southwards. The cocoon is strong and dense, and closed at each end, so that the thread is continuous, while the silk has a very strong and glossy fibre.
Next in value to the American silk worm, is the Ailanthus silk worm (Samia Cynthia) a species allied to our Callosamia Promethea. It originated from China, where it is cultivated, and was introduced into Italy in 1858, and thence spread into France, where it was introduced by M. Guerin-Meneville. Its silk is said to be much stronger than the fibre of cotton, and is a mean between fine wool and ordinary silk. The worm is very hardy, and can be reared in the open air both in this country and in Europe. The main drawback to its culture is the difficulty in unreeling the tough cocoon, and the shortness of the thread, the cocoon being open at one end.
The Yama-mai moth (Antheraea Yama-mai) was introduced into France from Japan in 1861. It is closely allied to the Polyphemus moth, and its caterpillar also feeds on the oak. Its silk is said to be quite brilliant, but a little coarser and not so strong as that of the Bombyx mori. The Perny silk worm is extensively cultivated by the Chinese in Manchouria, where it feeds on the oak. Its silk is coarser than that of the common silk worm, but is yet fine, strong and glossy. Bengal has furnished the Tussah moth, which lives in India on the oak and a variety of other trees. It is largely raised in French and English India, according to Nogues, and is used in the manufacture of stuffs called corahs.
The last kind of importance is the Arrhindy silk worm, from India. It has been naturalized in France and Algeria by M. Guerin-Meneville, who has done so much in the application of entomology to practical life. It is closely allied to the Cynthia or Ailanthus worm, with the same kind of silk and a similar cocoon, and feeds on the castor oil plant.
The diseases of silk worms naturally receive much attention. Like those afflicting mankind, they arise from bad air, resulting from too close confinement, bad food, and other adverse causes. The most fatal and wide-spread disease, and one which since 1854 has threatened the extermination of silk worms in Europe, is the pebrine. It is due to the presence of minute vegetable corpuscles, which attack both the worms and the eggs. It was this disease which swept off thousands of Mr. Trouvelot's Polyphemus worms, and put a sudden termination to his important experiments, the germs having been implanted in eggs of the Yama-mai moth imported from Japan by M. Guerin-Meneville, and which were probably infected as they passed through Paris. Though the disaster happened several years since, he tells us that it will be useless for him to attempt the raising of silk worms in the town where his establishment is situated, as the germs of the disease are most difficult to eradicate.
So direful in France were the ravages of this disease that two of the most advanced naturalists in France, Quatrefages and Pasteur, were commissioned by the French government to investigate the disease. Pasteur found that the infected eggs differed in appearance from the sound ones, and could thus be sorted out by aid of the microscope and destroyed. Thus these investigations, carried on year after year, and seeming to the ignorant to tend to no practical end, resulted in saving to France her silk culture. During the past year (1871) so successful has his method proved that a French scientific journal expresses the hope of the complete reestablishment and prosperity of this great industry. A single person who obtained in 1871 in his nurseries 30,000 ounces of eggs, hopes the next year to obtain 100,000 ounces, from which he expects to realize about one million dollars.
THE CLOTHES MOTH.
For over a fortnight we once enjoyed the company of the caterpillar of a common clothes moth. It is a little pale, delicate worm (Fig. 57, magnified), about the size of a darning needle, and rather less than half an inch in length, with a pale horn-colored head, the ring next the head being of the same color. It has sixteen feet, the first six of them well developed and constantly in use to draw the slender body in and out of its case. Its head is armed with a formidable pair of jaws, with which, like a scythe, it mows its way through thick and thin.
But the case is the most remarkable feature in the history of this caterpillar. Hardly has the helpless, tiny worm broken out of the egg, previously laid in some old garment of fur or wool, or perhaps in the haircloth of a sofa, when it begins to make a shelter by cutting the woolly fibres or soft hairs into bits, which it places at each end in successive layers, and, joining them together by silken threads, constructs a cylindrical tube (Fig. 58) of thick, warm felt, lined within with the finest silk the tiny worm can spin. The case is not perfectly cylindrical, being flattened slightly in the middle, and contracted a little just before each end, both of which are always kept open. The case before us is of a stone-gray color, with a black stripe along the middle, and with rings of the same color round each opening. Had the caterpillar fed on blue or yellow cloth, the case would, of course, have been of those colors. Other cases, made by larvae which had been eating loose cotton, were quite irregular in form, and covered loosely with bits of cotton thread, which the little tailor had not trimmed off.
Days go by. A vigorous course of dieting on its feast of wool has given stature to our hero. His case has grown uncomfortably small. Shall he leave it and make another? No housewife is more prudent and saving. Out come those scissor-jaws, and, lo! a fearful rent along each side of one end of the case. Two wedge-shaped patches mend the breach; the caterpillar retires for a moment and reappears at the other end; the scissors are once more pulled out; two rents appear, to be filled up by two more patches or gores, and our caterpillar once again breathes more freely, laughs and grows fat upon horse hair and lambs' wool. In this way he enlarges his case till he stops growing.
Our caterpillar seeming to be full-grown, and apparently out of employment, we cut the end of his case half off. Two or three days after, he had mended it from the inside, drawing the two edges together by silken threads, and, though he had not touched the outside, yet so neatly were the two parts joined together that we had to search for some time, with a lens, to find the scar.
To keep our friend busy during the cold, cheerless weather, for it was mid-winter, we next cut a third of the case entirely off. Nothing daunted, the little fellow bustled about, drew in a mass of the woolly fibres, filling up the whole mouth of his den, and began to build on afresh, and from the inside, so that the new-made portion was smaller than the rest of the case. The creature worked very slowly, and the addition was left in a rough, unfinished state.
We could easily spare these voracious little worms hairs enough to serve as food, and to afford material for the construction of their paltry cases; but that restless spirit that ever urges on all beings endowed with life and the power of motion, never forsakes the young clothes moth for a moment. He will not be forced to drag his heavy case over rough hairs and furzy wool, hence with his keen jaws he cuts his way through. Thus, the more he travels, the more mischief he does.
After taking his fill of this sort of life he changes to a chrysalid (Fig. 59), and soon appears as one of those delicate, tiny, demure moths that fly in such numbers from early in the spring until the autumn.
Very many do not recognize these moths in their perfect stage, so small are they, and vent their wrath on those great millers that fly around lamps in warm summer evenings. It need scarcely be said that these large millers are utterly guiltless of any attempts upon our wardrobes; they make their attacks in a more open form on our gardens and orchards.
We will give a more careful description of the clothes moth, which was found in its different stages June 12th in a mass of loose cotton. The larva is white, with a tolerably plump body, which tapers slightly towards the tail, while the head is much of the color of gum-copal. The rings of the body are thickened above, especially on the thoracic ones, by two transverse thickened folds. It is one-fifth of an inch long.
The body of the chrysalis, or pupa, is considerably curved, with the head smooth and rounded. The long antennae, together with the hind legs, which are folded along the breast, reach to the tip of the hind body, on the upper surface of each ring of which is a short transverse row of minute spines, which aid the chrysalis in moving towards the mouth of its case, just before the moth appears. At first the chrysalis is whitish, but just before the exclusion of the moth becomes the color of varnish.
When about to cast its pupa skin, the skin splits open on the back, and the perfect insect glides out. The act is so quickly over with, that the observer has to look sharp to observe the different steps in the operation.
Our common clothes moth (Tinea flavifrontella, Fig. 60) is of a uniform light-buff color, with a silky iridescent lustre, the hind wings and abdomen being a little paler. The head is thickly tufted with hairs and is a little tawny, and the upper side of the densely hirsute feelers (palpi) is dusky. The wings are long and narrow, with the most beautiful and delicate long silken fringe, which increases in length towards the base of the wing.
They begin to fly in May, and last all through the season, fluttering with a noiseless, stealthy flight in our apartments, and laying their eggs in our woollens.
Successive broods of the clothes moth appear through the summer. In the autumn they cease eating, retire within their cases, and early in spring assume the chrysalis state.
There are several allied species which have much the same habits, except that they do not all construct cases, but eat carpets, clothing, articles of food, grain, etc., and objects of natural history.
Careful housewives are not much afflicted with these pests. The slovenly and thriftless are overrun with them. Early in June woollens and furs should be carefully dusted, shaken and beaten. Dr. T. W. Harris states that "powdered black pepper, strewed under the edge of carpets, is said to repel moths. Sheets of paper sprinkled with spirits of turpentine, camphor in coarse powder, leaves of tobacco, or shavings of Russia leather, should be placed among the clothes when they are laid aside for the summer; and furs and other small articles can be kept by being sewed in bags with bits of camphor wood, red cedar, or of Spanish cedar; while the cloth lining of carriages can be secured forever from the attacks of moths by being washed or sponged on both sides with a solution of the corrosive sublimate of mercury in alcohol, made just strong enough not to leave a white stain on a black feather." The moths can be most readily killed by pouring benzine among them, though its use must be much restricted from the disagreeable odor which remains. The recent experiments made with carbolic acid, however, convince us that this will soon take the place of other substances as a preventive and destroyer of noxious insects.
THE MOSQUITO AND ITS FRIENDS.
The subject of flies becomes of vast moment to a Pharaoh, whose ears are dinned with the buzz of myriad winged plagues, mingled with angry cries from malcontent and fly-pestered subjects; or to the summer traveller in northern lands, where they oppose a stronger barrier to his explorations than the loftiest mountains or the broadest streams; or to the African pioneer, whose cattle, his main dependence, are stung to death by the Tsetze fly; or the fariner whose eyes on the evening of a warm spring day, after a placid contemplation of his growing acres of wheat blades, suddenly detects in dismay clouds of the Wheat midge and Hessian fly hovering over their swaying tops. The subject, indeed, has in such cases a national importance, and a few words regarding the main points in the habits of flies—how they grow, how they do not grow (after assuming the winged state), and how they bite; for who has not endured the smart and sting of these dipterous Shylocks, that almost torment us out of our existence while taking their drop of our heart's blood—may be welcome to our readers.
The Mosquito will be our first choice. As she leaps off from her light bark, the cast chrysalis skin of her early life beneath the waters, and sails away in the sunlight, her velvety wings fringed with silken hairs, and her neatly bodiced trim figure (though her nose is rather salient, considering that it is half as long as her entire body), present a beauty and grace of form and movement quite unsurpassed by her dipterous allies. She draws near and softly alights upon the hand of the charmed beholder, subdues her trumpeting notes, folds her wings noiselessly upon her back, daintily sets down one foot after the other, and with an eagerness chastened by the most refined delicacy for the feelings of her victim, and with the air of Velpeau redivivus, drives through crushed and bleeding capillaries, shrinking nerves and injured tissues, a many-bladed lancet of marvellous fineness, of wonderful complexity and fitness. While engorging herself with our blood, we will examine under the microscope the mosquito's mouth. The head (Fig. 61) is rounded, with the two eyes occupying a large part of the surface, and nearly meeting on the top of the head. Out of the forehead, so to speak, grow the long, delicate, hairy antennm (a), and just below arises the long beak which consists of the bristle-like maxillae (mx, with their palpi, mp) and mandibles (m), and the single hair-like labrum, these five bristle-like organs being laid in the hollowed labium (l). Thus massed into a single awl-like beak, the mosquito, without any apparent effort, thrusts them all except the labium into the flesh. Her hind body may be seen tilling with the red blood, until it cries quits, and the insect withdraws its sting and flies sluggishly away. In a moment the wounded parts itch slightly, though a very robust person may not notice the irritation, or a more delicate individual if asleep; though if weakened by disease, or if stung in a highly vascular and sensitive part, such as the eyelid, the bite becomes really a serious matter. Multiply the mosquito a thousand fold, and one flees their attacks and avoids their haunts as he would a nest of hornets. Early in spring the larva (Fig. 62, A) of the mosquito may be found in pools and ditches. It remains at the bottom feeding upon decaying matter (thus acting as a scavenger, and in this state doing great benefit in clearing swamps of miasms), until it rises to the surface for air, which it inhales through a single respiratory tube (c) situated near the tail. When about to transform into the pupa state, it contracts and enlarges anteriorly near the middle, the larval skin is thrown off, and the insect appears in quite a different form (Fig. 62, a). The head and thorax are massed together, the rudiments of the mouth parts and of the wings and legs being folded upon the breast, while there are two breathing tubes (d) situated upon the back instead of the tail, which ends in two broad paddles (a); so that it comes to the surface, head foremost instead of tail first, a position according better with its increased age and experience in pond life. In a few days the pupa skin is cast; the insect, availing itself of its old habiliments as a raft upon which to float while its body is drying, grows lighter, and its wings expand for its marriage flight. The males are beautiful, both physically and morally, as they do not bite; their manners are more retiring than those of their stronger minded partners, as they rarely enter our dwellings, and live unnoticed in the woods. They may be easily distinguished from the females by their long maxillary palpi, and their thick, bushy, feathered antennae. The female lays her elongated, oval eggs in a boat-shaped mass, which floats on the water. A mosquito lives three or four weeks in the water before changing to the adult or winged stage. How many days they live in the latter state we do not know.
Our readers will understand, then, that all flies, like our mosquito for example, grow while in the larva and pupa state, and after they acquire wings do not grow, so that the small midges are not young mosquitoes, but the adult winged forms of an entirely different species and genus of fly; and the myriads of small flies, commonly supposed to be the young of larger flies, are adult forms belonging to different species of different genera, and perhaps of different families of the suborder of Diptera. The typical species of the genus Culex, to which the mosquito belongs, is Culex pipiens, described by Linnaeus, and there are already over thirty North American species of this genus described in various works. Few insects live in the sea, but along the coast of New England a small, slender white larva (Fig. 63a, magnified, and head greatly enlarged; Fig. 64, pupa and fore foot of larva, showing the hooks), whose body is no thicker than a knitting needle, lives between tides, and has even been dredged at a depth of over a hundred feet, which transforms into a yellow mosquito-like fly (Fig. 65, with head of the female, magnified) which swarms in summer in immense numbers. I have called it provisionally Chironomus oceanicus, or Ocean gnat. The larvae of other species have been found by Mr. S. I. Smith living at great depths in our Northern lakes. These kinds of gnats are usually seen early in spring hovering in swarms in mid air.
The strange fact has been discovered by Grimm, a Russian naturalist, that the pupa of a feathered gnat is capable of laying eggs which produce young during the summer time. Previous to this it had been discovered that a larva of a gnat (Fig. 66 a, eggs from which the young are produced) which lives under the bark of trees in Europe, also produced young born alive.
The Hessian fly (Fig. 67, a, larva; b pupa; c, stalk of wheat injured by larvae) and Wheat midge, which are allied to the mosquito, are briefly referred to in the calendar, so that we pass over these to consider another pest of our forests and prairies.
The Black fly is even a more formidable pest than the mosquito. In the northern, subarctic regions, it opposes a barrier against travel. The Labrador fisherman spends his summer on the sea shore, scarcely daring to penetrate the interior on account of the swarms of these flies. During a summer residence on this coast, we sailed up the Esquimaux river for six or eight miles, spending a few hours at a house situated on the bank. The day was warm and but little wind blowing, and the swarms of black flies were absolutely terrific. In vain we frantically waved our net among them, allured by some rare moth; after making a few desperate charges in the face of the thronging pests, we had to retire to the house, where the windows actually swarmed with them; but here they would fly in our faces, crawl under one's clothes, where they even remain and bite in the night. The children in the house were sickly and worn by their unceasing torments; and the shaggy Newfoundland dogs whose thick coats would seem to be proof against their bites ran from their shelter beneath the bench and dashed into the river, their only retreat. In cloudy weather, unlike the mosquito, the black fly disappears, only flying when the sun shines. The bite of the black fly is often severe, the creature leaving a large clot of blood to mark the scene of its surgical triumphs. Prof. E. T. Cox, State Geologist of Indiana, has sent us specimens of a much larger fly, which Baron Osten Sacken refers to this genus, which is called on the prairies, where it is said to bite horses to death, the Buffalo Gnat. Westwood states that an allied fly (Rhagio Columbaschensis) is one of the greatest scourges of man and beast in Hungary, where it has been known to kill cattle.
The Simulium molestum (Fig. 68, enlarged), as the black fly is called, lives during the larva state in the water. The larva of a Labrador species (Fig. 69, enlarged) which we found, is about a quarter of an inch long, and of the appearance here indicated. The pupa is also aquatic, having long respiratory filaments attached to each side of the front of the thorax. According to Westwood, "the posterior part of its body is enclosed in a semioval membranous cocoon, which is at first formed by the larva, the anterior part of which is eaten away before changing to a pupa, so as to be open in front. The imago is produced beneath the surface of the water, its fine silky covering serving to repel the action of the water."
Multitudes of a long, slender, white worm may often be found living in the dirt, and sour sap running from wounds in the elm tree. Two summers ago we discovered some of these larvae, and on rearing them found that they were a species of Mycetobia (Fig. 70; a, larva; b, pupa). The larva is remarkable for having the abdominal segments divided into two portions, the hinder much smaller than the anterior division. Its whole length is a little over a third of an inch. The pupae were found sticking out in considerable numbers from the tree, being anchored by the little spines at the tail. The head is square, ending in two horns, and the body is straight and covered with spines, especially towards the end of the tail. They were a fifth of an inch in length. The last of June the flies appeared, somewhat resembling gnats, and about a line long. The worms continued to infest the tree for six weeks, the flies remaining either upon or near it.
We now come to that terror of our equine friends, the Horse fly, Gad, or Breeze fly. In its larval state, some species live in water, and in damp places under stones and pieces of wood, and others in the earth away from water, where they feed on animal, and, probably, on decaying matter. Mr. B. D. Walsh found an aquatic larva of this genus, which, within a short time, devoured eleven water snails. Thus at this stage of existence, this fly, often so destructive, even at times killing our horses, is beneficial. During the hotter parts of summer, and when the sun is shining brightly, thousands of these Horse flies appear on our marshes and inland prairies. There are many different kinds, over one hundred species of the genus Tabanus alone, living in North America. Our most common species is the "Green head," or Tabanus lineola. When about to bite, it settles quietly down upon the hand, face or foot, it matters not which, and thrusts its formidable lancet-like jaws deep into the flesh. Its bite is very painful, as we can testify from personal experience. We were told during the last summer that a horse, which stood fastened to a tree in a field near the marshes at Rowley, Mass., was bitten to death by these Green heads; and it is known that horses and cattle are occasionally killed by their repeated harassing bites. In cloudy weather they do not fly, and they perish on the cool frosty nights of September. The Timb, or Tsetze fly, is a species of this group of flies, and while it does not attack man, plagues to death, and is said to poison by its bite, the cattle in certain districts of the interior of Africa, thus almost barring out explorers. On comparing the mouth-parts of the Horse fly (Fig. 71, mouth of T. lineola), we have all the parts seen in the mosquito, but greatly modified. Like the mosquito, the females alone bite, the male Horse fly being harmless, and frequenting flowers, living upon their sweets. The labrum (lb), mandibles (m) and maxillae (mx), are short, stiff and lancet-like, and the maxillary palpi (mp; a, the five terminal joints of the antennae) are large, stout, and two-jointed. While the jaws (both maxillae and mandibles) are thrust into the flesh, the tongue (l) spreads around the tube thus formed by the lancets, and pumps up the blood flowing from the wound, by aid of the sucking stomach, or crop, being a sac appended to the throat. Other Gad flies, but much smaller, though as annoying to us in woods and fields, are the species of Golden eyed flies, Chrysops, which fly and buzz interminably about our ears, often taking a sudden nip. They plague cattle, settling upon them and drawing their blood at their leisure.
We turn to a comparatively unknown insect, which has occasionally excited some distrust in the minds of housekeepers. It is the carpet fly, Scenopinus pallipes (Fig. 72), which, in the larva state, is found under carpets, on which it is said to feed. The worm (Fig. 73) has a long, white, cylindrical body, divided into twelve segments, exclusive of the head, while the first eight abdominal segments are divided by a transverse suture, so that there appear to be seventeen abdominal segments, the sutures appearing too distinct in the cut. Mr. F. G. Sanborn has reared the fly, here figured, from the worm. The larva also lives in rotten wood; it is too scarce ever to prove very destructive in houses. Either this or a similar fly was once found, we are told by a scientific friend, in great numbers in a "rat" used in dressing a young lady's hair; the worms were living upon the hair stuffing.
One of the most puzzling objects to the collector of shells or insects, is the almost spherical larva of Microdon globosus (Fig. 74). It is flattened and smooth beneath and seems to adhere to the under side of stones, where it might be mistaken for a snail.
The Syrphus fly, or Aphis eater, deserves more than the passing notice which we bestow upon it. The maggot (Fig. 75, in the act of devouring an Aphis) is to be sought for established in a group of plant lice (Aphis), which it seizes by means of the long extensible front part of the body. The adult fly (Fig. 76) is gayly spotted and banded with yellow, resembling closely a wasp. It frequents flowers.
76. Syrphus Fly.]
The singular rat-tailed pupa-case of Eristalis (Fig. 77) lives in water, and when in want of air, protrudes its long respiratory tube out into the air. We present the figure of an allied fly, Merodon Bardus (Fig. 78; a, puparium, natural size). We will not describe at length the fly, as the admirable drawings of Mr. Emerton cannot fail to render it easily recognizable. The larva is much like the puparium or pupa case, here figured, which closely resembles that of Eristalis, in possessing along respiratory filament, showing that the maggot undoubtedly lives in the water, and when desirous of breathing, protrudes the tube out of the water, thus drawing in air enough to fill its internal respiratory tubes (tracheae). The Merodon Narcissa probably lives in the soil, or in rotten wood, as the pupa-case has no respiratory tube, having instead a very short, sessile, truncated tube, scarcely as long as it is thick. The case itself is cylindrical, and rounded alike at each end.
We now come to the Bot flies, which are among the most extraordinary, in their habits, of all insects. The history of the Bot flies is in brief thus. The adult two-winged fly lays its eggs on the exterior of the animal to be infested. They are conveyed into the interior of the host, where they hatch, and the worm or maggot lives by sucking in the purulent matter, caused by the irritation set up by its presence in its host; or else the worm itself, after hatching, bores under the skin. When fully grown, it quits the body and finishes its transformations to the fly-state under ground. Many quadrupeds, from mice, squirrels, and rabbits, up to the ox, horse, and even the rhinoceros, suffer from their attacks, while man himself is not exempt. The body of the adult fly is stout and hairy, and it is easily recognized by having the opening of the mouth very small, the mouth-parts being very rudimentary. The larvae are, in general, thick, fleshy, footless grubs, consisting of eleven segments, exclusive of the head, which are covered with rows of spines and tubercles, by which they move about within the body, thus irritating the animals in which they take up their abode. The breathing pores (stigmata) open in a scaly plate at the posterior end of the body. The mouth-parts (mandibles, etc.) of the subcutaneous larvae consist of fleshy tubercles, while in those species which live in the stomachs and frontal sinuses of their host, they are armed with horny hooks.
The larvae attain their full size after moulting twice. Just before assuming the pupa state, the maggot leaves its peculiar dwelling place, descends into the ground and there becomes a pupa, though retaining its larval skin, which serves as a protection to it, whence it is called a "puparium."
Several well-authenticated instances are on record of a species of bot fly inhabiting the body of man, in Central and South America, producing painful tumors under the skin of the arm, legs and abdomen. It is still under dispute whether this human bot fly is a true or accidental parasite, the more probable opinion being that its proper host is the monkey or dog. In Cayenne, this revolting grub is called the Ver macaque (Fig. 79); in Para, Ura; in Costa Rica, Torcel; and in New Granada, Gusano peludo, or Nuche. The Dermatobia noxialis, supposed to be the Ver moyocuil of the inhabitants of Mexico and New Granada, lives beneath the skin of the dog.
The Bot fly of the horse, (Gastrophilus equi, Fig. 80 and larva), is pale yellowish, spotted with red, with short, grayish, yellow hairs, and the wings are banded with reddish. She lays her eggs upon the knees of the horse. They are conveyed into the stomach, where the larva lives from May until October, and when full grown are found hanging by their mouth hooks on the edge of the rectum of the horse, whence they are carried out in the excrement. The pupa state lasts for thirty or forty days, and the perfect fly appears the next season, from June until October.
The Bot fly of the ox (Hypoderma bovis, Fig. 81, and larva), is black and densely hairy, and the thorax is banded with yellow and white. The larva is found during the month of May, and also in summer, living in tumors on the backs of cattle. When fully grown, which is generally in July, they make their way out and fall to the ground, and live in the pupa-case from twenty-six to thirty days, the fly appearing from May until September. It is found all over the world. The Oestrus ovis, or sheep Bot fly (Fig. 82, larva), is of a dirty ash color. The abdomen is marbled with yellowish and white flecks, and is hairy at the end. This species of Bot fly is larviparous, i.e., the eggs are hatched within the body of the mother, the larvae being produced alive. M. F. Brauer, of Vienna, the author of the most thorough work we have on these flies, tells me that he knows of but one other Bot fly (a species of Cephanomyia) which produces living larvae instead of eggs. The eggs of certain other species of Bot flies do not hatch until three or four days after they are laid. The larvae of the sheep Bot fly live, during April, May and June, in the frontal sinus of the sheep, and also in the nasal cavity, whence they fall to the ground when fully grown. In twenty-four hours they change to pupae, and the flies appear during the summer.
We also figure the Cuterebra buccata (Fig. 83; a, side view,) which resembles in the larval state the ox Bot fly. Its habits are not known, though the young of other species infest the opossum, squirrel, hare, etc., living in subcutaneous tumors.
THE HOUSE FLY AND ITS ALLIES.
The common House fly, Musca domestica, scarcely needs an introduction to any one of our readers, and its countenance is so well known that we need not present a portrait here. But a study of the proboscis of the fly reveals a wonderful adaptability of the mouth-parts of this insect to their uses. We have already noticed the most perfect condition of these parts as seen in the horse fly. In the proboscis of the house fly the hard parts are obsolete, and instead we have a fleshy tongue like organ (Fig. 84), bent up beneath the head when at rest. The maxillae are minute, their palpi (mp) being single-jointed, and the mandibles (m) are comparatively useless, being very short and small, compared with the lancet-like jaws of the mosquito or horse fly. But the structure of the tongue itself (labium, l) is most curious. When the fly settles upon a lump of sugar or other sweet object, it unbends its tongue, extends it, and the broad knob-like end divides into two broad, flat, muscular leaves (l), which thus present a sucker-like surface, with which the fly laps up liquid sweets. These two leaves are supported upon a framework of tracheal tubes. In the cut given above, Mr. Emerton has faithfully represented these modified trachae, which end in hairs projecting externally. Thus the inside of this broad fleshy expansion is rough like a rasp, and as Newport states, "is easily employed by the insect in scraping or tearing delicate surfaces. It is by means of this curious structure that the busy house fly occasions much mischief to the covers of our books, by scraping off the albuminous polish, and leaving tracings of its depredations in the soiled and spotted appearance which it occasions on them. It is by means of these also that it teases us in the heat of summer, when it alights on the hand or face to sip the perspiration as it exudes from, and is condensed upon, the skin."
Every one notices that house flies are most abundant around barns in August and September, and it is in the ordure of stables that the early stages of this insect are passed. No one has traced the transformations of this fly in our country, but we copy from Bouche's work on the transformations of insects, the rather rude figures of the larva (Fig. 85), and pupa-case (a) of the Musca domestica of Europe, which is supposed to be our species. Bouche states that the larva is cylindrical, rounded posteriorly, smooth and shining, fleshy, and yellowish white, and four lines long. The pupa-case, or puparium, is dark reddish-brown, and three lines in length. It remains in the pupa state from eight to fourteen days. In Europe it is preyed upon by minute ichneumon flies (Chalcids). The flesh fly, Musca Caesar, or the Blue-bottle fly, feeds upon decaying animal matter. Its larva (Fig. 86) is long, cylindrical, the head being pointed, and the body conical, the posterior end being squarely docked. The larva of a Sargus-like form which feeds on offal, transforms into a flattened pupa-case (Fig. 87), provided with long, scattered hairs. The House fly disappears in autumn, at the approach of cold weather, though a few individuals pass through the winter, hibernating in houses, and when the rooms are heated may often be seen flying on the windows. Other species fly early in March, on warm days, having hibernated under leaves, and the bark of trees, moss, etc. An allied species, the M. vomitoria, is the Meat fly. Closely allied are the parasitic species of Tachina, which live within the bodies of caterpillars and other insects, and are among the most beneficial of insects, as they prey on thousands of injurious caterpillars. Another fly of this Muscid group, the Idia Bigoti, according to Coquerel and Mondiere, produces in the natives of Senegal, hard, red, fluctuating tumors, in which the larva resides.
Many of the smaller Muscids mine leaves, running galleries within the leaf, or burrowing in seeds or under the bark of plants. We have often noticed blister-like swellings on the bark of the willow, which are occasioned by a cylindrical, short, fleshy larva (Fig. 88a, much enlarged), about a line in length, which changes to a pupa within the old larval skin, assuming the form here represented (Fig. 88b), and about the last of June changes to a small black fly (Fig. 88), which Baron Osten Sacken refers doubtfully to the genus Lonchaea.
The Apple midge frequently does great mischief to apples after they are gathered. Mr. F. G. Sanborn states that nine-tenths of the apple crop in Wrentham, Mass., were destroyed by a fly supposed to be the Molobrus mali, or Apple midge, described by Dr. Fitch. "The eggs were supposed to have been laid in fresh apples, in the holes made by the Coddling moth (Carpocapsa pomonella), whence the larvae penetrated into all parts of the apple, working small cylindrical burrows about one-sixteenth of an inch in diameter." Mr. W. C. Fish has also sent me, from Sandwich, Mass., specimens of another kind of apple worm, which he writes has been very common in Barnstable county. "It attacks mostly the earlier varieties, seeming to have a particular fondness for the old fashioned Summer, or High-top Sweet. The larvae (Fig. 89 a) enter the fruit usually where it has been bored by the Apple worm (Carpocapsa), not uncommonly through the crescent-like puncture of the curculio, and sometimes through the calyx, when it has not been troubled by other insects. Many of them arrive at maturity in August, and the fly soon appears, successive generations of the maggots following until cold weather. I have frequently found the pupae in the bottom of barrels in a cellar in the winter, and the flies appear in the spring. In the early apples, the larvae work about in every direction. If there be several in an apple, they make it unfit for use. Apples that appear perfectly sound when taken from the tree, will sometimes, if kept, be all alive with them in a few weeks." Baron Osten Sacken informs me that it is a Drosophila, "the species of which live in putrescent vegetable matter, especially fruits."
An allied fly is the parent of the cheese maggot. The fly itself (Piophila casei, Fig. 90) is black, with metallic green reflections, and the legs are dark and paler at the knee-joints, the middle and hind pair of tarsi being dark honey yellow. The Wine fly is also a Piophila, and lives the life of a perpetual toper in old wine casks, and partially emptied beer, cider and wine bottles, where, with its pupa-case (Fig. 91), it may be found floating dead in its favorite beverage.
We now come to the more degraded forms of flies which live parasitically on various animals. We figure, from a specimen in the Museum of the Peabody Academy of Science, the Bird tick (Ornithomyia, Fig. 92), which lives upon the Great Horned Owl. Its body is much flattened, adapted for its life under the feathers, where it gorges itself with the blood of its host.
Here belongs also the Horse tick (Hippobosca equina, Fig. 93). It is about the size of the house fly, being black, with yellow spots on the thorax. Verrill says that "it attacks by preference those parts where the hair is thinnest and the skin softest, especially under the belly and between the hind legs. Its bite causes severe pain, and will irritate the gentlest horses, often rendering them almost unmanageable, and causing them to kick dangerously. When found, they cling so firmly as to be removed with some difficulty, and they are so tough as not to be readily crushed. If one escapes when captured, it will instantly return to the horse, or, perchance, to the head of its captor, where it is an undesirable guest. Another species sometimes infests the ox."
In the wingless Sheep tick (Melophagus ovinus, Fig. 94, with the pupa-case on the left), the body is wingless and very hairy, and the proboscis is very long. The young are developed within the body of the parent, until they attain the pupa state, when she deposits the pupa case, which is nearly half as large as her abdomen. Other genera are parasitic on bats; among them are the singular spider-like Bat ticks (Nycteribia, Fig. 95), which have small bodies and enormous legs, and are either blind, or provided with four simple eyes. They are of small size, being only a line or two in length. Such degraded forms of Diptera have a remarkable resemblance to the spiders, mites, ticks, etc. The reader should compare the Nycteribia with the young six-footed moose tick figured farther on. Another spider-like fly is the Chionea valga (Fig. 96; and 97, larva of the European species), which is a degraded Tipula, The latter genus standing near the head of the Diptera. The Chionea, according to Harris, lives in its early, stages in the ground like many other gnats, and is found early in the spring, sometimes crawling over the snow. We have also figured and mentioned previously (page 41) the Bee louse, Braula, another wingless spider-like fly.
The Flea is also a wingless fly, and is probably, as has been suggested by an eminent entomologist, as Baron Osten Sacken informs us, a degraded genus of the family to which Mycetobia belongs. Its transformations are very unlike those of the fly ticks, and agree closely with the early stages of Mycetophila, one of the Tipulid family. In its adult condition the flea combines the characters of the Diptera, with certain features of the grasshoppers and cockroaches, and the bugs. The body of the flea (Fig. 98, greatly magnified; a, antennae; b, maxillae, and their palpi, c; d, mandibles; the latter, with the labium, which is not shown in the figure, forming the acute beak) is much compressed, and there are minute wing-pads, instead of wings, present in some species.
Dr. G. A. Perkins, of Salem, has succeeded in rearing in considerable numbers from the eggs, the larvae of this flea. The larvae (Fig. 99, much enlarged; a, antenna; b, the terminal segments of the abdomen), when hatched, are half a line in length. The body is long, cylindrical, and pure white, with thirteen segments exclusive of the head, and provided with rather long hairs. It is very active in its movements, and lives on blood clots, remaining on unswept floors of out-houses, or in the straw or bed of the animals they infest. In six days after the eggs are laid the larvae appear, and in a few days after leaving the egg they mature, spin a rude cocoon, and change to pupae, and the perfect insects appear in about ten days. A good authority states that the human flea does not exist in America. We never saw a specimen in this country.
A practical point is how to rid dogs of fleas. As a preventive measure, we would suggest the frequent sweeping and cleansing of the floors of their kennels, and renewing the straw or chips composing their beds,—chips being the best material for them to sleep upon. Flea afflicted dogs should be washed every few days in strong soapsuds, or weak tobacco or petroleum water.
A writer in "Science-Gossip" recommends the "use of the Persian Insect Destroyer, one package of which suffices for a good sized dog. The powder should be well rubbed in all over the skin, or the dog, if small, can be put into a bag previously dusted with the powder; in either case the dog should be washed soon after."
One of the most serious insect torments of the tropics of America is the Sarcopsylla penetrans, called by the natives the Jigger, Chigoe, Bicho, Chique, or Pique (Fig. 100, enlarged; a, gravid female, natural size). The female, during the dry season, bores into the feet of the natives, the operation requiring but a quarter of an hour, usually penetrating under the nails, and lives there until her body becomes distended with eggs, the hind-body swelling out to the size of a pea; her presence often causes distressing sores. The Chigoe lays about sixty eggs, depositing them in a sort of sac on each side of the external opening of the oviduct. The young develop and feed upon the swollen body of the parent flea until they mature, when they leave the body of their host and escape to the ground. The best preventive is cleanliness and the constant wearing of shoes or slippers when in the house, and of boots when out of doors.
THE BORERS OF OUR SHADE TREES.
In no way can the good taste and public spirit of our citizens be better shown than in the planting of shade trees. Regarded simply from a commercial point of view one cannot make a more paying investment than setting out an oak, elm, maple or other shade tree about his premises. To a second generation it becomes a precious heirloom, and the planter is duly held in remembrance for those finer qualities of heart and head, and the wise forethought which prompted a deed simple and natural, but a deed too often undone. What an increased value does a fine avenue of shade trees give to real estate in a city? And in the country the single stately elm rising gracefully and benignantly over the wayside cottage, year after year like a guardian angel sending down its blessings of shade, moisture and coolness in times of drought, and shelter from the pitiless storm, recalls the tenderest associations of generation after generation that go from the old homestead.
Occasionally the tree, or a number of them, sicken and die, or linger out a miserable existence, and we naturally after failing to ascribe the cause to bad soil, want of moisture or adverse atmospheric agencies, conclude that the tree is infested with insects, especially if the bark in certain places seems diseased. Often the disease is in streets lighted by gas, attributed to the leakage of the gas. Such a case has come up recently at Morristown, New Jersey. An elm was killed by the Elm borer (Compsidea tridentata), and the owner was on the point of suing the Gas Company for the loss of the tree from the supposed leakage of a gas pipe. While the matter was in dispute, a gentleman of that city took the pains to peel off a piece of the bark and found, as he wrote me, "great numbers of the larvae of this beetle in the bark and between the bark and the wood, while the latter is 'tattooed' with sinuous grooves in every direction and the tree is completely girdled by them in some places. There are three different sizes of the larvae, evidently one, two and three years old, or more properly six, eighteen and thirty months old." The tree had to be cut down.
Dr. Harris, in his "Treatise on Injurious Insects," gives an account of the ravages of this insect, which we quote: "On the 19th of June, 1846, Theophilus Parsons, Esq., sent me some fragments of bark and insects which were taken by Mr. J. Richardson from the decaying elms on Boston Common, and among the insects I recognized a pair of these beetles in a living state. The trees were found to have suffered terribly from the ravages of these insects. Several of them had already been cut down, as past recovery; others were in a dying state, and nearly all of them were more or less affected with disease or premature decay. Their bark was perforated, to the height of thirty feet from the ground, with numerous holes, through which insects had escaped; and large pieces had become so loose, by the undermining of the grubs, as to yield to slight efforts, and come off in flakes. The inner bark was filled with burrows of the grubs, great numbers of which, in various stages of growth, together with some in the pupa state, were found therein; and even the surface of the wood, in many cases, was furrowed with their irregular tracks. Very rarely did they seem to have penetrated far into the wood itself; but their operations were mostly confined to the inner layers of the bark, which thereby became loosened from the wood beneath. The grubs rarely exceed three-quarters of an inch in length. They have no feet, and they resemble the larvae of other species of Saperda, except in being rather more flattened. They appear to complete their transformations in the third year of their existence.
"The beetles probably leave their holes in the bark during the month of June and in the beginning of July, for, in the course of thirty years, I have repeatedly taken them at various dates, from the fifth of June to the tenth of July. It is evident, from the nature and extent of their depredations, that these insects have alarmingly hastened the decay of the elm trees on Boston Mall and Common, and that they now threaten their entire destruction. Other causes, however, have probably contributed to the same end. It will be remembered that these trees have greatly suffered, in past times, from the ravages of canker-worms. Moreover, the impenetrable state of the surface soil, the exhausted condition of the subsoil, and the deprivation of all benefit from the decomposition of accumulated leaves, which, in a state of nature, the trees would have enjoyed, but which a regard for neatness has industriously removed, have doubtless had no small influence in diminishing the vigor of the trees, and thus made them fall unresistingly a prey to insect devourers. The plan of this work precludes a more full consideration of these and other topics connected with the growth and decay of these trees; and I can only add, that it may be prudent to cut down and burn all that are much infested by the borers."
The Three-toothed Compsidea (Fig. 101), is a rather flat-bodied, dark brown beetle, with a rusty red curved line behind the eyes, two stripes on the thorax, and a three-toothed stripe on the outer edge of each wing cover. It is about one-half an inch in length.
The larva (Fig. 102) is white, subcylindrical, a little flattened, with the lateral fold of the body rather prominent; the end of the body is flattened, obtuse, and nearly as wide at the end as at the first abdominal ring. The head is one-half as wide as the prothoracic ring, being rather large. The prothoracic ring, or segment just behind the head, is transversely oblong, being twice as broad as long; there is a pale dorsal corneous transversely oblong shield, being about two-thirds as long as wide, and nearly as long as the four succeeding segments; this plate is smooth, except on the posterior half, which is rough, with the front edge irregular and not extending far down the sides. Fine hairs arise from the front edge and side of the plate, and similar hairs are scattered over the body and especially around the end. On the upper side of each segment is a transversely oblong ovate roughened area, with the front edge slightly convex, and the hinder slightly arcuate. On the under side of each segment are similar rough horny plates, but arcuate in front, with the hinder edge straight.
It differs from the larva of the Linden tree borer (Saperda vestita) in the body being shorter, broader, more hairy, with the tip of the abdomen flatter and more hairy. The prothoracic segment is broader and flatter, and the rough portion of the dorsal plates is larger and less tranversely ovate. The structure of the head shows that its generic distinctness from Saperda is well founded, as the head is smaller and flatter, the clypeus being twice as large, and the labrum broad and short, while in S. vestita it is longer than broad. The mandibles are much longer and slenderer, and the antennae are much smaller than in S. vestita.
The Linden tree borer (Fig. 103) is a greenish snuff-yellow beetle, with six black spots near the middle of the back; and it is about eight-tenths of an inch in length, though often smaller. The beetles, according to Dr. Paul Swift, as quoted by Dr. Harris, were found (in Philadelphia) upon the small branches and leaves on the 28th day of May, and it is said that they come out as early as the first of the month, and continue to make their way through the back of the trunk and large branches during the whole of the warm season. They immediately fly into the top of the tree, and there feed upon the epidermis of the tender twigs, and the petioles of the leaves, often wholly denuding the latter, and causing the leaves to fall. They deposit their eggs, two or three in a place, upon the trunk or branches especially about the forks, making slight incisions or punctures for their reception with their strong jaws. As many as ninety eggs have been taken from a single beetle. The grubs (Fig. 104, e; a, enlarged view of the head seen from above; b, the under view of the same: c, side view, and d, two rings of the body enlarged), hatched from these eggs, undermine the bark to the extent of six or eight inches, in sinuous channels, or penetrate the solid wood an equal distance. It is supposed that three years are required to mature the insect. Various expedients have been tried to arrest their course, but without effect. A stream, thrown into the tops of trees from the hydrant, is often used with good success to dislodge other insects; but the borer-beetles, when thus disturbed, take wing and hover over the trees till all is quiet, and then alight and go to work again. The trunks and branches of some of the trees have been washed over with various preparations without benefit. Boring the trunk near the ground and putting in sulphur and other drugs, and plugging, have been tried with as little effect.
The city of Philadelphia has suffered grievously from this borer.
Dr. Swift remarks, in 1844, that "the trees in Washington and Independence Squares were first observed to have been attacked about seven years ago. Within two years it has been found necessary to cut down forty-seven European lindens in the former square alone, where there now remain only a few American lindens, and these a good deal eaten." In New England this beetle should be looked for during the first half of June.
The Poplar tree is infested by an other species of Saperda (S. calcarata). This is a much larger beetle than those above mentioned, being an inch or a little more in length. It is grey, irregularly striped, with ochre, and the wing-covers end in a sharp point. The grub (Fig. 105 a; b, top view of the head; e, under side) is about two inches long and whitish yellow. It has, with that of the Broad-necked Prionus (P. laticollis of Drury, Fig. 106, adult and pupa), as Harris states, "almost entirely destroyed the Lombardy poplar in this vicinity" (Boston). It bores in the trunks, and the beetle flies by night in August and September. We also figure the larva of another borer (Fig. 107 c; a, top view of the head; b, under side; e, dorsal view of an abdominal segment; d, end of the body, showing its peculiar form), the Saperda inornata of Say, the beetle of which is black, with ash gray hairs, and without spines on the wing-covers. It is much smaller than any of the foregoing species, being nine-twentieths of an inch in length. Its habits are not known. We also figure the Locust and Hickory borer (Fig. 108; a, larva; b, pupa), which has swept off the locust tree from New England. The beautiful yellow banded beetles are very abundant on the flowers of the golden rod in September.
[Footnote 4: The External and Internal Parasites of Man and Domestic Animals. By Prof. A. E. Verrill, 1870. We are indebted to the author for the use of this and the figures of the Bot fly of the horse, the turkey, duck and hog louse, the Cattle tick, the itch insect and mange insect of the horse.]
CERTAIN PARASITIC INSECTS.
The subject of our discourse is not only a disagreeable but too often a painful one. Not only is the mere mention of the creature's name of which we are to speak tabooed and avoided by the refined and polite, but the creature itself has become extinct and banished from the society of the good and respectable. Indeed under such happy auspices do a large proportion of the civilized world now live that their knowledge of the habits and form of a louse may be represented by a blank. Not so with some of their great-great-grandfathers and grandmothers, if history, sacred and profane, poetry, and the annals of literature testify aright; for it is comparatively a recent fact in history that the louse has awakened to find himself an outcast and an alien. Among savage nations of all climes, some of which have been dignified with the apt, though high sounding name of Phthiriophagi, and among the Chinese and other semi-civilized peoples, these lords of the soil still flourish with a luxuriance and rankness of growth that never diminishes, so that we may say without exaggeration that certain mental traits and fleshly appetites induced by their consumption as an article of food may have been created, while a separate niche in our anthropological museums is reserved for the instruments of warfare, both offensive and defensive, used by their phthiriophagous hunters. Then have we not in the very centres of civilization the poor and degraded, which are most faithfully attended lay these revolting satellites!
But bantering aside, there is no more engaging subject to the naturalist than that of animal parasites. Consider the great proportion of animals that gain their livelihood by stealing that of others. While a large proportion of plants are more or less parasitic, they gain, thereby in interest to the botanist, and many of them are eagerly sought as the choicest ornaments of our conservatories. Not so with their zooelogical confreres. All that is repulsive and uncanny is associated with them, and those who study them, though perhaps among the keenest intellects and most industrious observers, speak of them without the limits of their own circle in subdued whispers or under a protest, and their works fall under the eyes of the scantiest few. But the study of animal parasites has opened up new fields of research, all bearing most intimately on those two questions that ever incite the naturalist to the most laborious and untiring diligence—what is life and its origin? The subjects of the alternation of generations, or parthenogenesis, of embryology and biology, owe their great advance, in large degree, to the study of such animals as are parasitic, and the question whether the origin of species be due to creation by the action of secondary laws or not, will be largely met and answered by the study of the varied metamorphoses and modes of growth, the peculiar modification of organs that adapt them to their strange modes of life, and the consequent variation in specific characters so remarkably characteristic of those animals living parasitically upon others.
With these considerations in view surely a serious, thoughtful, and thorough study of the louse, in all its varieties and species, is neither belittling nor degrading, nor a waste of time. We venture to say, moreover, that more light will be thrown on the classification and morphology of insects by the study of the parasitic species, and other degraded, wingless forms that do not always live parasitically, especially of their embryology and changes after leaving the egg, than by years of study of the more highly developed insects alone. Among Hymenoptera the study of the minute Ichueumons, such as the Proctotrupids and Chalcids, especially the egg-parasites; among moths the study of the wingless canker-worm moth and Orgyla; among Diptera the flea, bee louse, sheep tick, bat tick, and other wingless flies; among Coleoptera, the Meloe, and singular Stylops and Xenos; among Neuroptera, the snow insect, Boreus, the Podura (Fig. 109) and Lepisma, and especially the hemipterous lice, will throw a flood of light on these prime subjects in philosophical entomology.
Without farther apology, then, and very dependent on the labors of others for our information, we will say a few words on some interesting points in the natural history of lice. In the first place, how does the louse bite? It is the general opinion among physicians, supported by able entomologists, that the louse has jaws, and bites. But while the bird lice (Mallophaga) do have biting jaws, whence the Germans call them skin-eaters (pelzfresser), the mouth parts of the genus Pediculus, or true louse, resemble in their structure those of the bed-bug (Fig. 110), and other Hemiptera. In its form the louse closely resembles the bed-bug, and the two groups of lice, the Pediculi and Mallophaga, should be considered as families of Hemiptera, though degraded and at the base of the hemipterous series. The resemblance is carried out in the form of the egg, the mode of growth of the embryo, and the metamorphosis of the insect after leaving its egg.
Schioedte, a Danish entomologist, has, it seems to us, forever settled the question as to whether the louse bites the flesh or sucks blood, and decides a point interesting to physicians, i.e., that the loathsome disease called phthiriasis is a nonentity. From this source not only many living in poverty and squalor are said to have died, but also men of renown, among whom Denny in his work on the Anoplura, or lice, of Great Britain, mentions the name of "Pheretima, as recorded by Herodotus, Antiochus Epiphanes, the Dictator Sylla, the two Herods, the Emperor Maximian, and Phillip the Second." Schioedte, in his essay "On Phthirius, and on the Structure of the Mouth in Pediculus" (Annals and Magazine of Natural History, 1866, page 213), says that these statements will not bear examination, and that this disease should be placed on the "retired list," for such a malady is impossible to be produced by simply blood-sucking animals, and that they are only the disgusting attendants on other diseases. Our author thus describes the mouth parts of the louse.
"Lice are no doubt to be regarded as bugs, simplified in structure and lowered in animal life in accordance with their mode of living as parasites, being small, flattened, apterous, myopic, crawling and climbing, with a conical head, moulded as it were to suit the rugosities of the surface they inhabit, provided with a soft, transversely furrowed skin, probably endowed with an acute sense of feeling, which can guide them in that twilight in which their mode of life places them. The peculiar attenuation of the head in front of the antennae at once suggests to the practised eye the existence of a mouth adapted for suction. This mouth differs from that of the Hemiptera (bed-bug, etc.) generally, in the circumstance that the labium is capable of being retracted into the upper part of the head, which therefore presents a little fold, which is extended when the labium is protruded. In order to strengthen this part, a flat band of chitine is placed on the under surface, just as the shoemaker puts a small piece of gutta-percha into the back of an India-rubber shoe; as, however, the chitine is not very elastic, this band is rather thinner in the middle, in order that it may bend and fold a little when the skin is not extended by the lower lip. The latter consists, as usual, of two hard lateral pieces, of which the fore ends are united by a membrane so that they form a tube, of which the interior covering is a continuation of the elastic membrane in the top of the head; inside its orifice there are a number of small hooks, which assume different positions according to the degree of protrusion; if this is at its highest point the orifice is turned inside out, like a collar, whereby the small hooks are directed backwards, so that they can serve as barbs. These are the movements which the animal executes after having first inserted the labium through a sweat-pore. When the hooks have got a firm hold, the first pair of setae (the real mandibles transformed) are protruded; these are, towards their points, united by a membrane so as to form a closed tube, from which, again, is inserted the second pair of setae, or maxillae, which in the same manner are transformed into a tube ending in four small lobes placed crosswise. It follows that when the whole instrument is exserted, we perceive a long membranous flexible tube hanging down from the labium, and along the walls of this tube the setiform mandibles and maxillae in the shape of long narrow bands of chitine. In this way the tube of suction can be made longer or shorter as required, and easily adjusted to the thickness of the skin in the particular place where the animal is sucking, whereby access to the capillary system is secured at any part of the body. It is apparent, from the whole structure of the instrument, that it is by no means calculated on being used as a sting, but is rather to be compared to a delicate elastic probe, in the use of which the terminal lobes probably serve as feelers. As soon as the capillary system is reached, the blood will at once ascend into the narrow tube, after which the current is continued with increasing rapidity by means of the pulsation of the pumping ventricle and the powerful peristaltic movement of the digestive tube."
111. Mouth of the Louse.]
If we compare the form of the louse (Fig. 112, Pediculus capitis, the head louse; Fig. 113, P. vestimenti, the body louse) with the young bed-bug as figured by Westwood (Modern Classification of Insects, ii,.p. 475) we shall see a very close resemblance, the head of the young Cimex being proportionally larger than in the adult, while the thorax is smaller, and the abdomen is more ovate, less rounded; moreover the body is white and partially transparent.
Under a high power of the microscope specimens treated with diluted potash show that the mandibles and maxillae arise near each other in the middle of the head opposite the eyes, their bases slightly diverging. Thence they converge to the mouth, over which they meet, and beyond are free, being hollow, thin bands of chitine, meeting like the maxillae, or tongue, of butterflies to form a hollow tube for suction. The mandibles each suddenly end in a curved, slender filament, which is probably used as a tactile organ to explore the best sites in the flesh of their victim for drawing blood. On the other hand the maxillae, which are much narrower than the mandibles, become rounded towards the end, bristle like, and tipped with numerous exceedingly fine barbs, by which the bug anchors itself in the flesh, while the blood is pumped through the mandibles. The base of the large, tubular labium, or beak, which ensheathes the mandibles and maxillae, is opposite the end of the clypeus or front edge of the upper side of the head, and at a distance beyond the mouth equal to the breadth of the labium itself. The labium, which is divided into three joints, becomes flattened towards the tip, which is square, and ends in two thin membranous lobes, probably endowed with a slight sense of touch. On comparing these parts with those of the louse, it will be seen how much alike they are with the exception of the labium, a very variable organ in the Hemiptera. From the long sucker of the Pediculus, to the stout chitinous jaws of the Mallophaga, or bird lice, is a sudden transition, but on comparing the rest of the head and body it will be seen that the distinction only amounts to a family one, though Burmeister placed the Mallophaga among the Orthoptera (grasshoppers and crickets) on account of the mandibles being adapted for biting. It has been a common source of error to depend too much upon one or a single set of organs. Insects have been classified on characters drawn from the wings, or the number of the joints of the tarsi, or the form of the mouth parts. We must take into account in endeavoring to ascertain the limits of natural groups, as the internal anatomy and the embryology and metamorphosis of insects, before we can hope to obtain a natural classification.