GYPSY MOTH, a European Liparid moth (Porthetria dis par) brought to the United States for experiment in 1869 but escaped from confinement, multiplied slowly, and eventually be came a great woodland and orchard pest in New England. In 1888 and 1889 it had become very abundant in the vicinity of Medford, Mass., and its identity with the European species was ascertained. It was found to have spread over an area of nearly 400 sq.m. in the vicinity of Boston. For ten years effective work was carried on by the State of Massachusetts, and the insect was kept under measurable control. The State discontinued its work in 1900, and by 1905 it had spread over an area of approximately 4,000 sq.m. In 1906 it was found in the States of New Hampshire and Rhode Island. With the expansion of the infested area the Federal Gov ernment took active part in the work and since then has co operated with states in an effort to control and prevent its spread. These activities include the enforcement of a quarantine regulat ing the movement of articles which might carry the insect into new areas. The insect spread by natural means into new areas in the New England States, however, and in 1923 it was felt that natural spread to the west could best be prevented by eliminating all infestations which developed in an area along the eastern border of New York and adjoining States to the east. This barrier zone has since been maintained by the Federal Govern ment and the State of New York. Besides the infestation in New England, infestations have been found in a few other localities. The most extensive of these were in the vicinity of Rutherford, N.J., and Wilkes-Barre, Pa. These outlying infestations have generally been exterminated. Elimination of the infestations in New Jersey required persistent effort over a number of years and similar operations have made progress in Pennsylvania.
The adult female moth is a heavy-bodied, light coloured insect, with zigzag blackish marks on the wings. The body is so heavy that the female cannot fly. It has a wing-spread of 22 in. The male is much smaller, is dark in colour, and flies readily. The winter is passed in the egg stage. The eggs are laid in clusters of four hundred or more, on the bark of trees, on fence rails, fallen logs, under loose bark, in cavities in the trunks or branches and are sometimes placed on stones where they may be concealed from view. Each cluster is covered with buff-coloured hair. The eggs are laid during July, and hatch with the appearance of the leaves the following spring. The young larvae feed rapidly and become full-grown early in July. They are ravenous eaters, and when they are numerous the trees may be stripped completely before the end of June. The pupae, or chrysalids, into which the larvae are changed give out the adult moths after about ten days. There is one generation each year. The gypsy moth spreads commercially on nursery stock, young trees, lumber, stone or other products likely to be sent away. They also spread as newly hatched cater pillars, in which condition they are blown to considerable distances by the wind on warm sunny days. The insect is a very destructive enemy to mixed forests and to orchards. In New England thou sands of trees have been killed. Apple and oak have suffered more than other species, but pine and other coniferous trees have been killed when mixed with deciduous growth. The remedial measures adopted after long investigation have consisted of spraying with a solution of arsenate of lead, banding the trees to prevent the climbing of the caterpillars, and treatment of the egg-masses with creosote. Many species of parasites have been introduced from Europe, and certain of these, especially the Braconids and the Tachina flies, have proved reasonably effective. A predatory beetle known as Calosoma sycophants has also been introduced to good effect. These imported natural enemies have been the means of aiding very considerably in the control of the insect. (See