Scientific American Supplement, No. 803, May 23, 1891 | Page 7

growers in any given region were to destroy all the tents on their trees, even for a single season, the work of holding them in check or destroying them in the following year would be comparatively light.
[Illustration: FIG. 15.]
The moths, Fig. 16, appear in great numbers in July, their wings measuring, when expanded, from one and a quarter to one and a half inches or more. They are of a reddish brown color, the fore wings being tinged with gray on the base and middle, and crossed by two oblique whitish stripes.
[Illustration: FIG. 16.]
The females lay their eggs, about three hundred in number, in a belt, Fig. 15, c, around the twigs of apple, cherry, and a few other trees, the belt being covered by a thick coating of glutinous matter, which probably serves as a protection against the cold weather during winter.
The following spring, when the buds begin to swell, the egg hatch and the young caterpillar seek some fork of a branch, where they rest side by side. They are about one-tenth of an inch long, of a blackish color, with numerous fine gray hairs on the body. They feed on the young and tender leaves, eating on an average two apiece each day. Therefore the young of one pair of moths would consume from ten to twelve thousand leaves; and it is not uncommon to see from six to eight nests or tents on a single tree, from which no less than seventy-five thousand leaves would be destroyed--a drain no tree can long endure.
As the caterpillars grow, a new and much larger skin is formed underneath the old one, which splits along the back and is cast off. When fully grown, Fig. 15, a and b, which is in about thirty-five to forty days after emerging from the eggs, they are about two inches long, with a black head and body, with numerous yellowish hairs on the surface, with a white stripe along the middle of the back, and minute whitish or yellowish streaks, which are broken and irregular along the sides; and there is also a row of transverse, small, pale blue spots along each side of the back.
As they move about they form a continuous thread of silk from a fleshy tube on the lower side of the mouth, which is connected with the silk-producing glands in the interior of the body, and by means of this thread they appear to find their way back from the feeding grounds. It is also by the combined efforts of all the young from one belt of eggs that the tents are formed.
These caterpillars do not feed during damp, cold weather, but take two meals a day when it is pleasant.
After reaching their full growth, they leave their tents and scatter in all directions, seeking for some protected place where each one spins its spindle-shaped cocoon of whitish silk intermingled with sulphur colored powder, Fig. 15, d. They remain in these cocoons, where they have changed to pup?, from twenty to twenty-five days, after which the moths emerge, pair, and the females lay their eggs for another brood.
Several remedies have been suggested, a few of which are given below. Search the trees carefully, when they are bare, for clusters of eggs; and, when found, cut off the twigs to which they are attached, and burn them.
As soon as any tents are observed in the orchard they should be destroyed, which may be readily and effectually done by climbing the trees, and with the hand protected by a mitten or glove, seize the tent and crush it with its entire contents; also swab them down with strong soapsuds or other substances; or tear them down with a rounded bottle brush.
Burning with a torch not only destroys the caterpillars but injures the trees.
It should be observed, however, since the caterpillars, are quite regular in taking their meals, in the middle of the forenoon and afternoon, that they should be destroyed only in the morning or evening, when all are in the tent.
Another remedy is to shower the trees with Paris green in water, in the proportion of one pound to one hundred and fifty gallons of water.
THE FOREST TENT CATERPILLAR.
Clisiocampa disstria (Hübner.)
This species, commonly known as the forest tent caterpillar, closely resembles the apple tree tent caterpillar, but does not construct a visible tent. It feeds on various species of forest trees, such as oak, ash, walnut, hickory, etc., besides being very injurious to apple and other fruit trees. The moth, Fig. 17, b, expands an inch and a half or more. The general color is brownish yellow, and on the fore wings are two oblique brown lines, the space between them being darker than the rest of the wing. The eggs, Fig. 17, c and d, which are about