The idea failed and Trouvelot returned to France but not before some of the insects escaped from his laboratory. Since the turn of the century, gypsy moth caterpillars have stripped oak and other broad-leaf forests bare throughout the northeastern United States. Strict quarantines and eradication attempts failed to prevent the slow spread. Gypsy moths first moved into Ontario near Kingston over 20 years ago. By 1985, the insect had become a serious problem in southeastern Ontario and has continued to expand its range in the province.
Gypsy moths move into new areas either naturally or by hitching a ride on equipment or materials.
Natural spread can occur on the ground or by wind transport and is most rapid where there is a suitable food source. Areas with red and white oak, white birch and poplar are preferred by the gypsy moth. The insect usually thrives in forests containing these trees. People can have an impact on gypsy moth survival long before the caterpillars hatch by searching for the buff-coloured eggs and destroying them. Masses of eggs are easiest to see when leaves are off trees.