GYPSY MOTH

Close-up of a, ovipositing female; b, male; c, female pupa; d, male pupa; e, old egg mass. Larvae on oak leaf: f, First instar; g, second instar; h, fourth instar; i, sixth instar, or mature larva. Egg masses, k, under branches and on rock; 1, young larvae spinning down. (a to i, about natural size; k and 1, reduced.)

GYPSY MOTH

The gypsy moth is a serious foe of forest and shade trees in New England and eastern New York State. The caterpillars, or larvae, of these moths eat the leaves. The defoliation retards the growth and otherwise weakens the trees. Repeated complete defoliation may kill the trees.

This moth was accidentally introduced into this country in 1869. It spread rapidly through several Northeastern States. For many years the infested area has been under Federal quarantine. In part of the area suppressive measures have been carried out by State, local, and Federal agencies.

The gypsy moth larvae usually appear about the first of May. By the middle of June they are about 2 inches long. They have several pairs of red and blue dots on their backs. Late in June or early in July they become mature and seek shady places, such as on trees or rocks, in which to pupate and transform into moths. The moths emerge about a month later. The males are strong daytime fliers, but the females cannot fly and so lay their eggs close to the place where they issued as moths. The eggs are laid in clusters of 400 or more, which are covered with brownish hairs. The winter is passed in the egg stage.

Control: The gypsy moth can be controlled most effectively with DDT. An oil solution or an emulsion containing this insecticide is applied as a spray while the insect is in the caterpillar stage.

Large forested areas usually are sprayed from aircraft. For use along highways and residential areas, mist blowers or hydraulic sprayers are suitable. For treating low growth along stone walls and fences, sprayers of the knapsack type can be employed. Early in the season the spray should be applied at the rate of 1 pound of actual DDT per acre; after the foliage has developed, three-fourths pound per acre is sufficient.

Because of the many difficulties involved in formulation, it is best to obtain proprietary DDT insecticides and prepare them according to the manufacturers' instructions. Concentrated DDT solutions for use in blowers or aircraft are available on the market in 9- and 12-percent solutions. Apply at the rate of 1 gallon per acre to give, respectively, either the three-fourths or 1 pound dosage of actual DDT. If emulsion concentrates are used they should be diluted with water in the amounts suggested on the package to produce the desired three-fourths or 1 pound per acre coverage.