Without question, the Gypsy Moth is the most important insect defoliator of mixed hardwood forests in Eastern Canada and the Northeast United States. Over the past few years it has spread westwards and has been found as far west as British Columbia, where an Asian strain of Gypsy Moth has also found its way into the province.
Although the Gypsy Moth has a dietary preference for oak species, it is known to attack up to 300 different plant species when the population pressure of the insect increases, and food sources diminish.
Annual emergence of the adult moth occurs in July / August, and is followed almost immediately by mating. The female moths are short-lived (usually a week) and even though they may mate several times, they will generally only lay one egg-mass of 600-800 eggs on the bark of suitable trees, or even on rocks.
These eggs stay over winter and the larvae hatch out in May of the following year. After hatching, the larvae feed voraciously on tree foliage until late June or early July, when they pupate (form cocoons), emerging a few days later as adult Gypsy Moths.
The dark brown male moth is the first to emerge, and is smaller than the female. It flies well and lives for several weeks. The larger female moth is a light buff colour, and is a poor flyer, often seen fluttering across the ground because of her heavy body weight.