Scientific American Supplement, No. 803, May 23, 1891 | Page 8

one twenty fifth of an inch long and one fortieth wide, are arranged, three or four hundred in a cluster, around the twigs of the trees, Fig. 17, a. These clusters are uniform in diameter and cut off squarely at the ends. The eggs are white, and are firmly fastened to the twigs and to each other, by a brown substance, like varnish, which dries, leaving the eggs with a brownish covering.
[Illustration: FIG. 17.]
The eggs hatch about the time the buds burst, or before, and the young caterpillars go for some time without food, but they are hardy and have been known to live three weeks with nothing to eat, although the weather was very cold.
[Illustration: FIG. 18.]
As soon as hatched they spin a silken thread wherever they go, and when older wander about in search for food. The caterpillars are about one and a half inches long when fully grown, Fig. 18. The general color is pale blue, tinged with greenish low down on the sides, and everywhere sprinkled with black dots or points, while along the middle of the back is a row of white spots each side of which is an orange yellow stripe, and a pale, cream yellow stripe below that. These stripes and spots are margined with black. Each segment has two elevated black points on the back, from each of which arise four or more coarse black hairs. The back is clothed with whitish hairs, the head is dark bluish freckled with black dots, and clothed with black and fox-colored hairs, and the legs are black, clothed with whitish hairs.
At this stage the caterpillars may be seen wandering about on fences, trees, and along the roads in search of a suitable place to spin their cocoons, which are creamy white, and look very much like those of the common tent caterpillar, except that they are more loosely constructed.
Within the cocoons, in two or three days they transform to pup? of a reddish brown color, densely clothed with short pale yellowish hairs. The moths appear in two or three weeks, soon lay their eggs and then die. The insects are not abundant many years in succession, as their enemies, the parasites, increase and check them.
Many methods have been suggested for their destruction, but the most available and economical are to remove the clusters of eggs whenever found, and burn them, and to shower the trees with Paris green in the proportion of one pound to one hundred and fifty gallons of water.
THE STALK BORER.
Gortyna nitela (Gruen.)
The perfect moth, Fig. 19, 1, expands from one to one and a half inches. The fore wings are a mouse gray color, tinged with lilac and sprinkled with fine yellow dots, and distinguished mainly by a white band extending across the outer part. The moths hibernate in the perfect state, and in April or May deposit their eggs singly on the outside of the plant upon which the young are to feed. As soon as the eggs hatch, which is in about a month, the young larv?, or caterpillars, gnaw their way from the outside into the pith.
[Illustration: FIG. 19.]
The plant does not show any sign of decay until the caterpillar is fully grown, when it dies. The caterpillar, Fig. 19, 2, is about one and one-fourth inches long, of a reddish brown color, with whitish stripes along the body. The stripes on the sides are not continuous, and the shading of the body varies, being darker on the anterior than on the posterior portion. When fully grown, Fig. 20, the color is lighter and the stripes are broader. At this stage of life it burrows into the ground just beneath the surface, and changes into the pupa state. The pupa is three-fourths of an inch long, and of a mahogany brown color. The perfect moth appears about the first of September, and there is only one brood in a season.
[Illustration: FIG. 20.]
The caterpillars feed in the stalks of corn, tomatoes, potatoes, dahlias, asters, and also in young currant bushes, besides feeding on many species of weeds. By a close inspection of the plants about the beginning of July, the spot where the borer entered, which is generally quite a distance from the ground, may be detected, and the caterpillar cut out without injury to the plant. This plan is impracticable for an extensive crop, but by destroying the borers found in the vines that wilt suddenly, one can lessen the number another year.
THE PYRAMIDAL GRAPEVINE CATERPILLAR.
Pyrophila pyramidoides (Guen.)
This caterpillar, Fig. 21, is generally found on grapevines early in June, but also feeds on apple, plum, raspberry, maple, poplar, etc. It is about an inch and a half in length, with the body tapering toward the head; of a whitish green color, darker on the sides; with a longitudinal