« PreviousContinue »
It is very
in great abundance on the horse-radish, various kinds of cresses, and on the mustard, and turnip, early in May, and indeed at other times throughout the summer. injurious to young plants, destroying their seed-leaves as soon as the latter expand. Should it multiply to any extent, it may, in time, become as great a pest as the European turnip flea-beetle, which it closely resembles in its appearance, and in all its habits. Though rather larger than the cucumber fleabeetle, and of a longer oval shape, it is considerably less than one tenth of an inch in length. It is of a polished black color, with a broad wavy buff-colored stripe on each wing-cover, and the knees and feet are reddish yellow. Specimens are sometimes found having two buff-yellow spots on each wing-cover instead of the wavy stripe. These were not known, by Fabricius, to be merely varieties of the striolata, and accordingly he described them as distinct, under the name of bipustulata," the two-spotted.
The steel-blue flea-beetle, Haltica chalybea of Illiger, or the grape-vine flea-beetle, as it might be called on account of its habits, is found in almost all parts of the United States, on wild and cultivated grape-vines, the buds and leaves of which it destroys. Though it has received the specific name of chalybea, meaning steel-blue, it is exceedingly variable in its color, specimens being often seen on the same vine, of a dark purple, violet, Prussian blue, greenish blue, and deep green color. The most common tint of the upper side is a glossy, deep, greenish blue; the under side is dark green; and the antennæ and feet are dull black. The body is oblong-oval, and the hinder part of the thorax is marked with a transverse furrow. It measures rather more than three twentieths of an inch in length. In this part of the country these beetles begin to come out of their winter quarters towards the end of April, and continue to appear till the latter part of May. Soon after tneir first appearance they pair, and probably lay their eggs on the leaves of the vine, and perhaps on other plants also. A second brood of the beetles is found on the grape-vines towards
• Crioceris bipustulata, Fabricius.
the end of July. I have not had an opportunity to trace the history of these insects any further, and consequently their larvæ are unknown to me. Mr. David Thomas has given an interesting account of their habits and ravages in the twentysixth volume of Silliman's “ American Journal of Science and Arts." These brilliant insects were observed by him, in the spring of 1831, in Cayuga County, N. Y., creeping on the vines, and destroying the buds, by eating out the central succulent parts. Some had burrowed even half their length into the buds. When disturbed, they jump rather than fly, and remain where they fall for a time without motion. During the same season these beetles appeared in unusually great numbers in New Haven, Conn., and its vicinity, and the injury done by them was “wholly unexampled.” “Some vines were entirely despoiled of their fruit buds, so as to be rendered, for that season, barren.” Mr. Thomas found the vine-leaves were infested, in the years 1830 and 1831, by "small chestnut-colored smooth worms," and suspecting these to be the larvæ of the beetle (which he called Chrysomela vitivora), he fed them in a tumbler, containing some moist earth, until they were fully grown, when they buried themselves in the earth. “After a fortnight or so," some of the beetles were found in the tumbler. Hence there is no doubt that the former were the larvæ of the beetles, and that they undergo their transformations in the ground. A good description of the larvæ, and a more full
count of their habits, seasons, and changes, are still wanted.
In England, where the ravages of the turnip flea-beetle have attracted great attention, and have caused many and various experiments to be tried with a view of checking them, it is thought that “the careful and systematic use of lime will obviate, in a great degree, the danger which has been experienced" from this insect. From this and other statements in favor of the use of lime, there is good reason to hope that it will effectually protect plants from the various kinds of fleabeetles, if dusted over them, when wet with dew, in proper season. Watering plants with alkaline solutions, it is said, will kill the insects without injuring the plants. The solution may be made by dissolving one pound of hard soap in twelve gallons of the soap-suds left after washing. This mixture should be applied twice a day with a water-pot. Köllar very highly recommends watering or wetting the leaves of plants with an infusion or tea of wormwood, which prevents the fleabeetles from touching them. Perhaps a decoction of walnutleaves might be equally serviceable. Great numbers of the beetles may be caught by the skilful use of a deep bag.net of muslin, which should be swept over the plants infested by the beetles, after which the latter may be easily destroyed. This net cannot be used with safety to catch the insects on very young plants, on account of the risk of bruising or breaking their tender leaves.
The Chrysomelians, CHRYSOMELADE, properly so called, form the third family of the tribe to which I have given the same name, because these insects hold the chief place in it, in respect to size, beauty, variety, and numbers. These leaf-beetles are mostly broad oval, sometimes nearly hemispherical, in their form, or very convex above and flat beneath. The head is rather wide, and not concealed under the thorax. The latter is short, and broad behind. The antennæ are about half the length of the body, and slightly thickened towards the end, and arise from the sides of the head, between the eyes and the corners of the mouth; being much further apart than those of the Galerucians and flea-beetles. The legs are rather short, nearly equal in length, and the hindmost thighs are not thicker than the others, and are not fitted for leaping. The colors of these beetles are often rich and brilliant, among which blue and green, highly polished, and with a golden or metallic lustre, are the most common tints. The larvæ are soft-bodied, short, thick, and slug-shaped grubs, with six legs before, and a prop-leg behind. They live exposed on the leaves of plants, which they eat, and to which most of them fasten themselves by the tail, when about to be transformed. Some, however, go into the ground when about to change to pupæ. Many of these insects, both in the larva and beetle state, have been found to be very injurious to vegetation in other countries; but I am not aware that any of them have proved seriously injurious to cultivated or other valuable plants in this country. There are some, it is true, which may hereafter increase so as to give us much trouble, unless effectual means are taken to protect and cherish their natural enemies, the birds.
The largest species in New England inhabits the common milk-weed, or silk-weed (Asclepias Syriaca), upon which it may be found, in some or all of its states, from the middle of June till September. Its head, thorax, body beneath, antennæ, and legs are deep blue, and its wing-covers orange, with three large black spots upon them, namely, one on the shoulder, and another on the tip of each, and the third across the base of both wing-covers. Hence it was named Chrysomela trimaculata by Fabricius, or the three-spotted Chrysomela. It is nearly three eighths of an inch long, and almost hemispherical. Its larvæ and pupæ are orange-colored, spotted with black, and pass through their transformations on the leaves of the Asclepias.
The most elegant of our Chrysomelians is the Chrysomela scalaris of Leconte, literally the ladder Chrysomela. It is about three tenths of an inch long, and of a narrower and more regularly oval shape than the preceding. The head, thorax, and under side of its body are dark green, the wingcovers silvery white, ornamented with small green spots on the sides, and a broad jagged stripe along the suture or inner edges; the antennæ and legs are rust-red, and the wings are rose-colored. It is a most beautiful object when flying, with its silvery wing-covers, embossed with green, raised up, and its rose-red wings spread out beneath them. These beetles inhabit the lime or linden (Tilia Americana), and the elm, upon which they may be found in April, May, and June, and a second brood of them in September and October. They pass the winter in holes, and under leaves and moss. The trees on which they live are sometimes a good deal injured by them and by their larvæ. The latter are hatched from eggs laid by the beetles on the leaves in the spring, and come to their growth towards the end of June. They are then about six tenths of an inch long, of a white color, with a black line along the top of the back, and a row of small square black spots on each side of the body; the head is horny and of an ochre-yellow color. Like the grubs of the preceding species, these are short, and very thick, the back arching upwards very much in the middle. I believe that they go into the ground to turn to pupa.
Should they become so numerous as seriously to injure the lime and elm trees, it may be found useful to throw decoctions of tobacco or of walnut leaves on the trees by means of a garden or fire engine, a method which has been employed with good effect for the destruction of the larvæ of Galeruca Calmariensis.
The most common leaf-beetle of the family under consideration is the blue-winged Chrysomela, or Chrysomela cæruleipennis of Say, an insect hardly distinct from the European Chrysomela Polygoni, and like the latter it lives in great numbers on the common knot-grass (Polygonum aviculare), which it completely strips of its leaves two or three times in the course of the summer. This little beetle is about three twentieths of an inch long. Its head, wing-covers, and body beneath are dark blue; its thorax and legs are dull orange-red; the upper side of its abdomen is also orange-colored; and the antennæ and feet are blackish. The females have a very odd appearance before they have laid their eggs, their abdomen being enormously swelled out like a large orange-colored ball, which makes it very difficult for them to move about. I have found these insects on the knot-grass in every month from April to September inclusive. The larvæ eat the leaves of the same plant.
Having described the largest, the most elegant, and the most common of our Chrysomelians, I must omit all the rest, except the most splendid, which was called Eumolpus auratus by Fabricius, that is, the gilded Eumolpus. It is of a brilliant golden green color above, and of a deep purplish green below; the legs are also purple-green; but the feet and the antennæ are blackish. The thorax is narrower behind than the wingcovers, and the rest of the body is more oblong oval than in the foregoing Chrysomelians. It is about three eighths of an inch long
This splendid beetle may be found in considerable numbers on the leaves of the dog's-bane (Apocynum Androsemifolium), which it devours, during the months of July and August. The larvæ are unknown to me.