Gypsy Moth Trapping

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WSDA places up to 22,000 gypsy moth traps throughout the state each year. Traps are used for detecting the presence of moths and are not used for eradication. Only caterpillars inflict damage to vegetation. Since the traps attract only the adult males, traps placed near residences do not represent any increased threat of damage by gypsy moth to homeowners.

Traps are constructed of either green or orange cardboard. The inside of the trap is coated with a sticky viscous substance that ensnares insects when they land or crawl inside the trap (left photo). A lure, composed of string coated with a synthetic pheromone (right photo), is also placed inside the trap. A pheromone is a substance emitted by females to attract males during mating. Males, searching for females are drawn by the scent of the pheromone and become caught to the sticky inside of the trap.

WSDA crews check traps for gypsy moths every few weeks during the flight season (July to September). Once a gypsy moth is caught, the number and location of the trap is recorded and the specimen is sent to a USDA laboratory in Otis, Massachusetts for identification. Data from these surveys are incorporated in a national database of gypsy moth information.