Our Common Insects Part 5

Among some of the injurious insects reported on by Mr. Riley, the State Entomologist of Missouri, is a new pest to the cuc.u.mber in the West, the Pickle worm (Phacellura nitidalis, Fig. 46). This is a caterpillar which bores into the cuc.u.mbers when large enough to pickle, and which is occasionally found in pickles. Three or four worms sometimes occur in a cuc.u.mber, 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 (Ch.o.e.rocampa 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.

[Ill.u.s.tration: 48. Vine Dresser Moth.

47. Vine Dresser and Chrysalis.]

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 (Psych.o.m.orpha 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. 52_a_, larva; _b_, pupa; _c_, coc.o.o.n; _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 mult.i.tudes of the poorer cla.s.ses, 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.

[Ill.u.s.tration: 49. Eight-spotted Alypia and Larva.]

[Ill.u.s.tration: 50. Eudryas grata.]

[Ill.u.s.tration: 51. Larva of Psych.o.m.orpha.]

[Ill.u.s.tration: 52. American Procris and Young.]

[Ill.u.s.tration: 53. Larvae of American Procris.]

Silk culture is rapidly a.s.suming 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, coc.o.o.n), can, we are a.s.sured 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 coc.o.o.ns 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 coc.o.o.n, 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 j.a.pan 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 coc.o.o.n 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.

[Ill.u.s.tration: 54. American Silk Worm.]

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 coc.o.o.n, and the shortness of the thread, the coc.o.o.n being open at one end.

The Yama-ma moth (Antheraea Yama-ma) was introduced into France from j.a.pan 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 coa.r.s.er 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 coa.r.s.er 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.

[Ill.u.s.tration: 55. Chrysalis of American Silk Worm.]

[Ill.u.s.tration: 56. Coc.o.o.n of American Silk Worm.]

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 coc.o.o.n, 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-ma moth imported from j.a.pan by M. Guerin-Meneville, and which were probably infected as they pa.s.sed 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, Quatref.a.ges 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.

[Ill.u.s.tration: The Potato Caterpillar.]

CHAPTER V.

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.

[Ill.u.s.tration: 59. 58. 57.

Early Stages of the Clothes Moth.]

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 ma.s.s 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 ma.s.s 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.

[Ill.u.s.tration: 60. Clothes Moth.]

Our common clothes moth (Tinea flavifrontella, Fig. 60) is of a uniform light-buff color, with a silky iridescent l.u.s.tre, 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 a.s.sume 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 coa.r.s.e 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.

[Ill.u.s.tration: The Juniper Sickle-wing.]