Mamestra arctica, (Hadena amica, of Harris, and H. amputatrix, of Fitch), is a Cut-worm of a brownish color, about one and a half inch long. It is sometimes quite destructive in the nursery and garden, ascending woody plants, and cutting them off where succulent, in the month of May. It can only be checked by seeking for it, in the soil, near the base of the plants affected.
All these Cut-worms are eaten by birds, among which the crow is a valuable aid to the farmer, and should be cherished for his services instead of being condemned as a bird of ill-omen. Predacious insects also consume numbers of them; one of these is the larva of a beetle, Harpalus calaginosus. A large Ichneumon-fly has been found hunting after the worms, and is considered their natural enemy.
GEOMETERS, SPAN-WORMS, CANKER-WORMS.
The measuring worms take their name from their peculiar method of locomotion; having their legs at each end of their long bodies, they walk by progressive leaps, arching up their backs by bringing their hind-legs forward, and then thrusting their heads out to their full length. Many of them drop from the trees, and hang suspended by a thread of silk, when disturbed, or when seeking the earth to undergo their transformations. Some of them are naked, or have few hairs; most are smooth, often striped, or of an uniform color, like the bark of the trees on which they feed.
The moths are slender-bodied; the wings large; of some the females have no wings. These are the Hybernians, including the Canker-worm, Anisopterix vernata. These caterpillars are very numerous and destructive; they do not feed gregariously, and are difficult to combat in that form. The pupæ are under ground, and, as the female moths are wingless, and must ascend the trees to deposit their eggs, we can destroy them in the perfect form by meeting them on the highway they have to pass. Ingenious devices have been invented for this purpose; among the most effective of these are vessels of oil, fastened closely around the bole of the tree. The moths emerge from the ground in early spring, but many come out during pleasant mild days in the winter, and some even in the autumn; so the remedies must be applied early to be of any use.
Harris describes a smaller species as the Anisopterix pometaria.
Hybernia tiliaria, or the Span-worm of the Linden, is abundant in June, growing to the length of an inch and a half. A belt of tar, applied to the trees, has been found effective in preventing the ascent of the wingless females; this needs renewing daily, until the season of their rising has passed.
Ellopia ribearia, or the Currant-moth, was figured and described by Fitch as the Abraxas? ribearia, in New York Reports for 1856. The worm is light yellow, with black dots. It eats the leaves of currants and gooseberries, in June. The moth ascends from the ground in July; it is nankeen-yellow; quite a common insect in some parts of the country. It must have some natural enemies, for, where very abundant one year, it sometimes disappears altogether the next. Hand-picking is the only remedy known, and this is quite a tedious process.
TORTRICES, DELTA MOTHS, OR LEAF-ROLLERS.