« PreviousContinue »
depredations of one of these Nonagrians, known to our farmers by the name of the spindle-worm. The Rev. L. W. Leonard has favored me with a specimen of this insect, its chrysalis, and its moth, together with some remarks upon its habits; and the latter have also been described to me by an intelligent friend, conversant with agriculture. This insect receives its common name from its destroying the spindle of the Indian corn; but its ravages generally begin while the corn-stalk is young, and before the spindle rises much above the tuft of leaves in which it is embosomed. The mischief is discovered by the withering of the leaves, and, when these are taken hold of, they may often be drawn out with the included spindle. On examining the corn, a small hole may be seen in the side of the leafy stalk, near the ground, penetrating into the soft centre of the stalk, which, when cut open, will be found to be perforated, both upwards and downwards, by a slender wormlike caterpillar, whose excrementitious castings surround the orifice of the hole. This caterpillar grows to the length of an inch, or more, and to the thickness of a goose-quill. It is smooth, and apparently naked, yellowish, with the head, the top of the first and of the last rings black, and with a double row, across each of the other rings, of small, smooth, slightly elevated, shining black dots. With a magnifying glass a few short hairs can be seen on its body, arising singly from the black dots. This mischievous caterpillar is not confined to Indian corn, it attacks also the stems of the Dahlia, as I am informed, both by Mr. Leonard, and by the Rev. J. L. Russell, both of whom have observed its ravages in the stems of this favorite flower. It has also been found in the pith of the elder, and the same species of moth was produced from it, early in August, as from the spindle-worm of corn. The chrysalis, which is lodged in the burrow formed by the caterpillar, is slender, but not quite so long in proportion to its thickness as are those of most of the Nonagrians. It is shining mahoganybrown, with the anterior edges of four of the rings of the back roughened with little points, and four short spines or hooks, turned upwards, on the hinder extremity of the body. The moth produced from this insect differs from the other Nonagrians somewhat in form, its fore wings being shorter and more rounded at the tip. It may be called Gortyna* Zea, the corn Gortyna; Zea being the botanical name of Indian corn. The fore wings are rust-red; they are mottled with gray, al. most in bands, uniting with the ordinary spots, which are also gray and indistinct; there is an irregular tawny spot near the tip, and on the veins there are a few black dots. The hind wings are yellowish gray, with a central dusky spot, behind which are two faint, dusky bands. The head and thorax are rust-red, with an elevated tawny tuft on each. The abdomen is pale brown, with a row of tawny tufts on the back. The wings expand nearly one inch and a half.
In order to check the ravages of these insects they must be destroyed while in the caterpillar state. As soon as our cornfields begin to show, by the withering of the leaves, the usual signs that the enemy is at work in the stalks, the spindleworms should be sought for and killed; for, if allowed to remain undisturbed until they turn to moths, they will make their escape, and we shall not be able to prevent them from laying their eggs for another brood of these pestilent insects.
A worm, or caterpillar, something like the spindle-worm, has often been found by farmers in potato-stalks; and the potatorot has sometimes been ascribed to its depredations. On the ninth of July, 1848, one of these caterpillars was brought to me in a potato-stalk from Watertown; and, on the fifth of July, 1851, I found another within the stem of the pig-weed, or Chenopodium. These caterpillars were of a livid hue, faintly striped with three whitish lines along the back. Their transformations have not yet been observed.
The roots of the Columbine are attacked by another caterpillar belonging to this family. It burrows into the bottom of the stalk and devours the inside of the roots, which it injures so much that the plant soon dies. One of these caterpillars, which was found in July, in the roots of a fine double Columbine in my garden, was of a whitish color, with a few black
Gortyna, in ancient geography, was the name of a city in Crete, so called from its founder.
dots on each of the rings, a brownish head, and the top of the first and of the last rings blackish. It grew to the length of about one inch and a quarter, turned to a chrysalis on the nineteenth of August, and came out a moth on the twentyfourth of September. The moth closely resembles the Gortyna flavago of Europe, but is sufficiently distinct from it. It may be called Gortyna leucostigma, the white-spot Gortyna. The fore wings are tawny yellow, sprinkled with purple-brown dots, and with two broad bands and the outer hind margin purplebrown; there is a distinct tawny yellow spot on the tip, followed by a row of faint yellowish crescents between the brown band and margin; the ordinary spots are yellow, margined with brown, and there is a third oval spot of a white color near the round spot. The hind wings are pale buff or yellowish white, with a central spot, and a band behind it, of a brownish color. The head is brown; the thorax is tawny yellow, with a brown tuft; and the edges of the collar, and of the shoulder-covers are brown. The wings expand rather more than one inch and a half. I have what appear to be varieties of this moth, expanding one inch and three eighths, with three or four white dots around the kidney-spot, and the ordinary round spot wholly white.
Numerous complaints have been made of the ravages of cut-worms among corn, wheat, grass, and other vegetables, in various parts of the country. After a tiresome search through many of our agricultural publications, I have become convinced that these insects and their history are not yet known to some of the very persons who are said to have suffered from their depredations. Various cut-worms, or more properly subterranean caterpillars, wire-worms or Iuli, and grub-worms, or the young of May-beetles, are often confounded together or mistaken for each other; sometimes their names are interchanged, and sometimes the same name is given to each and all of these different animals. Hence the remedies that are successful in some instances are entirely useless in others. The name of cut-worm seems originally to have been given to certain caterpillars that live in the ground about the roots of plants, but come up in the night, and cut off and devour the tender stems and lower leaves of young cabbages, beans, corn, and other herbaceous plants. These subterranean caterpillars are finally transformed to moths belonging to a group which may be called Agrotidians (AGROTIDIDE), from a word signifying rustic, or pertaining to the fields. Some of these rustic moths fly by day, and may be found in the fields, especially in the autumn, sucking the honey of flowers; others are on the wing only at night, and during the day lie concealed in chinks of walls and other dark places. Their wings are nearly horizontal when closed, the upper pair completely covering the lower wings, and often overlapping a little on their inner edges, thus favoring these insects in their attempts to obtain shelter and concealment. The thorax is slightly convex, but smooth or not crested. The antennæ of the males are generally beset with two rows of short points, like fine teeth, on the under side, nearly to the tips. The fore legs are often quite spiny. Most of these moths come forth in July and August, and soon afterwards lay their eggs in the ground, in ploughed fields, gardens, and meadows. In Europe it is found that the eggs are hatched early in the autumn, at which time the little subterranean'caterpillars live chiefly on the roots and tender sprouts of herbaceous plants. On the approach of winter they descend deeper into the ground, and, curling themselves up, remain in a torpid state till the following spring, when they ascend towards the surface, and renew their devastations. The caterpillars of the Agrotidians are smooth, shining, naked, and dark-colored, with longitudinal pale and blackish stripes, and a few black dots on each ring; some of them also have a shining, horny, black spot on the top of the first ring. They are of a cylindrical form, tapering a little at each end, rather thick in proportion to their length, and are provided with sixteen legs. They are changed to chrysalids in the ground, without previously making silken cocoons. The most destructive kinds in Europe are the caterpillars of the corn rustic or winter dart-moth (Agrotis segetum), the wheat dart-moth (Agrotis tritici), the eagle-moth (Agrotis aquilina), and the turf rustic or antler-moth (Charæas graminis*). The first two attack both the roots and leaves of winter wheat; the second also destroys buckwheat; and it is stated that sixty bushels of mould, taken from a field where they prevailed, contained twenty-three bushels of the caterpillars; those of the eagle-moth occasionally prove very destructive in vineyards; and the caterpillars of the antler-moth are notorious for their devastations in meadows, and particularly in mountain pastures.
The habits of our cut-worms appear to be exactly the same as those of the European Agrotidians. It is chiefly during the months of June and July that they are found to be most destructive. Whole corn-fields are sometimes laid waste by them. Cabbage-plants, till they are grown to a considerable size, are very apt to be cut off and destroyed by them. Potatovines, beans, beets, and various other culinary plants suffer in the same way.
The products of our flower-gardens are not spared; asters, balsams, pinks, and many other kinds of flowers are often shorn of their leaves and of their central buds, by these concealed spoilers. Several years ago I procured a considerable number of cut-worms in the months of June and July. Some of them were dug up among cabbage-plants, some from potato-hills, and others from the corn-field and the flower-garden. Though varying in length from one inch and a quarter to two inches, they were fully grown, and buried themselves immediately in the earth with which they were supplied. They were all thick, greasy-looking caterpillars, of a dark ashen gray color, with a brown head, a blackish horny spot on the top of the first and last rings, a pale stripe along the back, and several minute black dots on each ring. They were soon changed to chrysalids, of a shining mahogany-brown color; and between the twentieth of July and the fifteenth of August they came out of the ground in the moth state. Much to my surprise, however, these cut-worms produced five different species of moths; and, when it was too late, I regretted that they had not been more carefully examined, and compared together before their transformation.
See “Köllar's Treatise," pp. 94, 102, 166, and 136.