Page images

The fourth family of the leaf-eating Chrysomelians consists of the Cryptocephalians (Cryptocephalidz), so named from the principal genus Cryptocephalus, a word signifying concealed head. These insects somewhat resemble the beetles of the preceding family; but they are of a more cylindrical form, and the head is bent down, and nearly concealed in the fore part of the thorax. Their larvæ are short, cylindrical, whitish grubs, which eat the leaves of plants. Each one makes for itself a little cylindrical or egg-shaped case, of a substance sometimes resembling clay, and sometimes like horn, with an opening at one end, within which the grub lives, putting out its head and fore legs when it wishes to eat or to move. When it is fully grown, it stops up the open end of its case, and changes to a рира, , and afterwards to a beetle within it, and then gnaws a hole through the case, in order to escape. As none of these insects have been observed to do much injury to plants in this country, I shall state nothing more respecting them, than that Clythra dominicana inhabits the sumach, C. quadriguttata oaktrees, Chlamys gibbosa low whortleberry bushes, Crytocephalus luridus the wild indigo-bush, and most of the other species may be found on different kinds of oaks.

Although the blistering beetles, or Cantharides (CANTHARIDIDÆ), have been enumerated among the insects directly beneficial to man, on account of the important use made of them in medical practice, yet it must be admitted that they are often very injurious to vegetation. The green Cantharides, or Spanish flies, as they are commonly called, are found in the South of Europe, and particularly in Spain and Italy, where they are collected in great quantities for exportation. In these countries they sometimes appear in immense swarms, on the privet, lilac, and ash; so that the limbs of these plants bend under their weight, and are entirely stripped of their foliage by these leafeating beetles. In like manner our native Cantharides devour the leaves of plants, and sometimes prove very destructive to them.

The Cantharides are distinguished from all the preceding insects by their feet, the hindmost pair of which have only four joints, while the first and middle pairs are five-jointed. In this respect they agree with many other beetles, such as clocks or darkling beetles, meal-beetles, some of the mushroom-beetles, flat bark-beetles, and the like, with which they form a large and distinct section of Coleopterous insects. The following are the most striking peculiarities of the family to which the blistering beetles belong. The head is broad and nearly heartshaped, and it is joined to the thorax by a narrow neck. The antennæ are rather long and tapering, sometimes knotted in the middle, particularly in the males. The thorax varies in form, but is generally much narrower than the wing-covers. The latter are soft and flexible, more or less bent down at the sides of the body, usually long and narrow, sometimes short and overlapping on their inner edges. The legs are long and slender; the soles of the feet are not broad, and are not cushioned beneath; and the claws are split to the bottom, or double, so that there appear to be four claws to each foot. The body is quite soft, and when handled, a yellowish fluid, of a disagreeable smell, comes out of the joints. These beetles are timid insects, and when alarmed they draw up their legs and feign themselves dead. Nearly all of them have the power of raising blisters when applied to the skin, and they retain it even when dead and perfectly dry. It is chiefly this property that renders them valuable to physicians. Four of our native Cantharides have been thus successfully employed, and are found to be as powerful in their effects as the imported species. For further particulars relative to their use, the reader is referred to my account of them published in 1824, in the first volume of “ The Boston Journal of Philosophy, and the Arts," and in the thirteenth volume of “ The New England Medical and Surgical Journal."

Occasionally potato-vines are very much infested by two or three kinds of Cantharides, swarms of which attack and destroy the leaves during midsummer. One of these kinds has thereby obtained the name of the potato-fly. It is the

Cantharis vittata," or striped Cantharis. It is of a dull tawny yellow or light yellowish red color above, with two black spots on the head, and two black stripes on the thorax and on each of the wing-covers. The under side of the body, the legs, and the antennæ are black, and covered with a grayish down. Its length is from five to six tenths of an inch. In this and the three following species the thorax is very much narrowed before, and the wing-covers are long and narrow, and cover the whole of the back. The striped Cantharis is comparatively rare in New England; but in the Middle and Western States it often appears in great numbers, and does much mischief in potato-fields and gardens, eating up not only the leaves of the potato, but those of many other vegetables. It is one of the insects to which the production of the potato-rot has been ascribed. The habits of this kind of Cantharis are similar to those of the following species.

There is a large blistering beetle which is very common on the virgin's bower (Clematis Virginiana), a trailing plant, which grows wild in the fields, and is often cultivated for covering arbors. I have sometimes seen this plant completely stripped of its leaves by these insects, during the month of August. They are very shy, and when disturbed fall immediately from the leaves, and attempt to conceal themselves among the grass. They most commonly resort to the low branches of the Clematis, or those that trail upon the ground, and more rarely attack the upper parts of the vine. They also eat the leaves of various kinds of Ranunculus or buttercups, and, in the Middle and Southern States, those of Clematis viorna and crispa. This beetle is the Cantharis marginata of Olivier, or margined Cantharis. It measures six or seven tenths of an inch in length. Its head and thorax are thickly covered with short gray down, and have a black spot on the upper side of each; the wing-covers are black, with a very narrow gray edging; and the under side of the body and the legs are also gray.

The most destructive kind of Cantharis, found in Massachusetts, is of a more slender form than the preceding, and measures only from five and a half to six tenths of an inch in length. Its antennæ and feet are black, and all the rest of its body is ashen gray, being thickly covered with a very short down of that color. Hence it is called Cantharis cinerea, or the ash-colored Cantharis. When the insect is rubbed, the ash-colored substance comes off, leaving the surface black. It begins to appear in gardens about the twentieth of June, and is very fond of the leaves of the English bean, which it sometimes entirely destroys. It is also occasionally found in considerable numbers on potato-vines; and in Cambridge, Massachusetts, it has repeatedly appeared in great profusion upon hedges of the honey-locust, which have been entirely stripped of foliage by these voracious insects. They are also found on the wild indigo-weed. In the night, and in rainy weather, they descend from the plants, and burrow in the ground, or under leaves and tufts of grass. Thither also they retire for shelter during the heat of the day, being most actively engaged in eating in the morning and evening. About the first of August they go into the ground and lay their eggs, and these are hatched in the course of one month. The larvæ are slender, somewhat flattened grubs, of a yellowish color, banded with black, with a small reddish head, and six legs. These grubs are very active in their motions, and appear to live upon fine roots in the ground; but I have not been able to keep them till they arrived at maturity, and therefore know nothing further of their history.

* Lytta vittata, Fabricius.

About the middle of August, and during the rest of this and the following month, a jet-black Cantharis may be seen on potato-vines, and also on the blossoms and leaves of various kinds of golden-rod, particularly the tall golden-rod (Solidago altissima), which seems to be its favorite food. In some places it is as plentiful in potato-fields as the striped and the margined Cantharis, and by its serious ravages has often excited attention. These three kinds, in fact, are often confounded under the common name of potato-flies; and it is still more

Lytta cinerea, Fabricius.

remarkable, that they are collected for medical use, and are sold in our shops by the name of Cantharis vittata, without a suspicion of their being distinct from each other. The black Cantharis, or Cantharis atrata," is totally black, without bands or spots, and measures from four tenths to half of an inch in length. I have repeatedly taken these insects, in considerable quantities, by brushing or shaking them from the potato-vines into a broad tin pan, from which they were emptied into a covered pail containing a little water in it, which, by wetting their wings, prevented their flying out when the pail was uncovered. The same method may be employed for taking the other kinds of Cantharides, when they become troublesome and destructive from their numbers; or they may be caught by gently sweeping the plants they frequent with a deep muslin bag-net. They should be killed by throwing them into scalding water, for one or two minutes, after which they may be spread out on sheets of paper to dry, and may be made profitable by selling them to the apothecaries for medical use.

There are some blistering beetles, belonging to another genus, which seem deserving of a passing notice, not on account of any great injury committed by them, but because they can be used in medicine like the foregoing, and are considered by some naturalists as forming one of the links connecting the orders Coleoptera and Orthoptera together. These insects belong to the genus Meloe, so named, it is supposed, because they are of a black, or deep blue-black color. They are called oil-beetles, in England, on account of the yellowish liquid which oozes from their joints in large drops when they are handled. Their head is large, heart-shaped, and bent down, as in the other blistering beetles. Their thorax is narrowed behind, and very small in proportion to the rest of the body. The latter is egg-shaped, pointed behind, and so enormously large, that it drags on the ground when the beetle attempts to walk. The wings are wanting, and of course these insects are unable to fly, although they have a pair of very short oval wing-covers, which overlap on their inner edges,


* Lytta atrata, Fabricius.

« PreviousContinue »