Our Common Insects Part 4

[Ill.u.s.tration: 39. Female Stylops.]

On carefully drawing out the whole body (Pl. 1, Fig. 6, as seen from above, and showing the alimentary ca.n.a.l ending in a blind sac; Fig.

6_a_, side view), which is very extensible, soft and baggy, and examining it under a high power of the microscope, we saw mult.i.tudes, at least several hundred, of very minute larvae, like particles of dust to the naked eye, issuing in every direction from the body of the parent now torn open in places, though most of them made their exit through an opening on the under side of the head-thorax. The Stylops, being hatched while still in the body of the parent, is, therefore viviparous. She probably never lays eggs.

On the last of April, when the Mezereon was in blossom, I caught the singular looking male (Stylops Childreni, Fig. 40; a, side view; it is about one-fourth of an inch long), which was as unlike its partner as possible. I laid it under a tumbler, when the delicate insect flew and tumbled about till it died of exhaustion in a few hours.

It appears, then, that the larvae are hatched during the middle or last of June from eggs fertilized in April. The larvae then crawl out upon the body of the bee, on which they are transported to the nest, where they enter, according to Peck's observations, the body of the larva, on whose fatty parts they feed. Previous to changing to a pupa the larva lives with its head turned towards that of its host, but before a.s.suming the perfect state (which they do in the late summer or autumn) it must reverse its position. The female protrudes the front part of her body between the segments of the abdomen of her host, as represented in our figure. This change, Newport thinks, takes place after the bee-host has undergone its metamorphoses, though the bee does not leave her earthen cells until the following spring. Though the male Stylops deserts his host, his wingless partner is imprisoned during her whole life within her host, and dies immediately after giving birth to her myriad (for Newport thinks she produces over two thousand) offspring.

[Ill.u.s.tration: 40. Male Stylops.]

Xenos Peckii, an allied insect, was discovered by Dr. Peck to be parasitic in the body of wasps, and there are now known to be several species of this small but curious family, Stylopidae, which are known to live parasitically on the bodies of our wild bees and wasps. The presence of these parasites finally exhausts the host, so that the sterile female bee dies prematurely.

As in the higher animals, bees are afflicted with parasitic worms which induce disease and sometimes death. The well-known hair worm, Gordius, is an insect parasite. The adult form is about the size of a slender knitting needle, and is seen in moist soil and in pools. It lays, according to Dr. Leidy, "millions of eggs connected together in long cords." The microscopical, tadpole-shaped young penetrate into the bodies of insects frequenting damp localities. Fairly ensconced within the body of their unsuspecting host, they luxuriate on its fatty tissues, and pa.s.s through their metamorphoses into the adult form, when they desert their living house and take to the water to lay their eggs.

In Europe, Siebold has described Gordius subbifurcus, which infests the drones of the Honey bee, and also other insects. Professor Siebold has also described Mermis albicans, which is a similar kind of hair worm, from two to five inches long, and whitish in color. This worm is also found, strangely enough, only in the drones, though it is the workers which frequent watery places to appease their thirst.

[Ill.u.s.tration: 41. Bee fungus.]

Thousands of insects are carried off yearly by parasitic fungi. The ravages of the Muscardine, caused by a minute fungus (Botrytris Ba.s.siana), have threatened the extinction of silk culture in Europe, and the still more formidable disease called _pebrine_ is thought to be of vegetable origin. Dr. Leidy mentions a fungus which must annually carry off myriads of the Seventeen Year Locust. A somewhat similar fungus, Mucor mellitophorus (Fig. 41), infests bees, filling the stomach with microscopical colorless spores, so as greatly to weaken the insect.

As there is a probability that many insects, parasites on the wild bees, may sooner or later afflict the Honey bee, and also to ill.u.s.trate farther the complex nature of insect parasitism, we will for a moment look at some other bee parasites.

[Ill.u.s.tration: Pl. 1

PARASITES OF BEES.]

Among the numerous insects preying in some way upon the Humble bee are to be found other species of bees and moths, flies and beetles. Insect parasites often imitate their host: Apathus (Plate I, Fig. 1, A.

Ashtoni) can scarcely be distinguished from its host, and yet it lives cuckoo-like in the cells of the Humble bee, though we know not yet how injurious it really is. Then there are Conops and Volucella, the former of which lives like Tachina and Phora within the bee's body, while the latter devours the brood. The young (Plate I, Figs. 5, 5_a_) of another fly allied to Anthomyia, of which the Onion fly (Fig. 42) is an example, is also not unfrequently met with. A small beetle (Plate 1.

Fig. 4, Antherophagus ochraceus) is a common inmate of Humble bees'

nests, and probably feeds upon the wax and pollen. We have also found several larvae (Fig. 43) of a beetle of which we do not know the adult form. Of similar habits is probably a small moth (Nephopteryx Edmandsii, Plate I, Figs. 2; 2_a_, larva; Fig. 2_b_, chrysalis, or pupa) which undoubtedly feeds upon the waxen walls of the bee cells, and thus, like the attacks of the common bee moth (Galleria cereana, whose habits are so well known as not to detain us, must prove very prejudicial to the well being of the colony. This moth is in turn infested by an Ichneumon fly (Microgaster nephoptericis, Plate I, Figs. 3, 3_a_) which must prove quite destructive.

[Ill.u.s.tration: 42. Onion Fly and Maggot.]

[Ill.u.s.tration: 43. Larva of Beetle.]

The figures of the early stages of a minute ichneumon represented on the same plate (Fig. 7, larva, and 7_a_, pupa, of Anthophorabia megachilis) which is parasitic on Megachile, the Leaf-cutter bee, ill.u.s.trates 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; 9_a_, 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.

CHAPTER IV.

A FEW WORDS ABOUT MOTHS.

The b.u.t.terflies 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, Hubner, 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 b.u.t.terflies 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 t.i.tle 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 ill.u.s.trates the early stages of many of our b.u.t.terflies 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 b.u.t.terflies 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 b.u.t.terfly attain their maturity only by pa.s.sing through wonderful changes of form and modes of life.

The knowledge of the fact that all animals pa.s.s 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 circ.u.mstantial 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 cla.s.sification 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 ill.u.s.trated 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 G.o.dard, 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 b.u.t.terflies 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 pota.s.sium 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 subst.i.tute 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.

[Ill.u.s.tration: 43. Parasite of the American Silk Worm.]

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).

[Ill.u.s.tration: 44. Tachina, parasite of Colorado Potato Beetle.]

[Ill.u.s.tration: 45. The Lace-winged Fly, Its 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 b.u.t.terfly (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 Ma.s.sachusetts 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 a.s.saults.

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 gra.s.s, 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, s.m.u.t 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 ill.u.s.trated 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.

[Ill.u.s.tration: 46. Pickle Worm and its Moth.]