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Gypsy Moths

Without question, the Gypsy Moth is the most important insect defoliator of mixed hardwood forests in Eastern Canada and the North East 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.


The Gypsy Moth trap only attracts the male adult moth, consequently female moths in the area may never become mated and either lay infertile eggs or none at all which has a significant impact on the following yearís Gypsy Moth population.

To ensure the maximum effectiveness of the traps, it is essential that they be placed in the area before the first male moths hatch out. They should be hung up in the first week of July.

Each kit consists of 5 traps with sticky inserts and pheromone attractant lures. These traps should be hung at equal spacing around the property, preferably at head height so that they can be easily inspected. Follow the assembly instructions and place the lure on the top of the insert when you slide it into the base of the trap. It should stick to the glued surface, or you can use a paper clip to attach it.

An even spread of traps on properties of approximately 1/2 acre provides a powerful attraction to the male moths and they will find it difficult to locate the short-lived females. Where possible neighbouring property owners should also be encouraged to use traps, since the effect will be greater. Where high populations of moths are present, it is possible to catch 300 or more moths in a single trap. Additional trap inserts are available.

The lures are packaged in foil pouches and once taken out and placed in the trap are effective for 3 or more months, which will easily cover the adult moth activity period. The traps can be brought in at the end of summer and can often be used again the following year with new inserts and lures. Traps can be disposed of in the regular garbage.

No special protective equipment is needed to handle the lures, but it is recommended that hands be washed before handling the lures (so as not to contaminate the lures) and also after handling them (so that the moths arenít attracted to you!). Rubber gloves may be worn since the non-drying glue can be sticky to handle. Unopened lure packets may be stored up to 5 years in a freezer, and are best contained in a glass jar so as to isolate them from any other products.

Inspect the traps from time to time to see whether they are catching moths and if the inserts become full, replace them, but continue to use the same lure. If a trap does not catch anything, move it to a different location where catches may be higher.

Many homeowners use these traps every season, and in doing so have been able to suppress the moth population to acceptable levels. Additional precautions such as scraping egg masses from the bark of trees in the fall, winter or early spring will further suppress the problem.

Until one has witnessed the complete defoliation that this insect can cause, it is difficult to appreciate the serious measure is well advised."

Of note:

The city of Toronto encountered a serious enough problem in May 2013 that they had to resort to aerial spraying. The MPOA are providing the above information to help answer questions. The information was taken from the supplier of traps: Our aim is to protect our forests around the lake for next year.