What You Can Do To Prevent the
Establishment of Gypsy Moth

How can you help?

Gypsy moth are transported into B.C. primarily by the movement of people and their possessions from infested parts of the country.  By looking for egg masses and evidence of other gypsy moth life stages and contacting the appropriate officials, you can be of great assistance in our efforts to keep this pest out of the province.

Where to Find Egg Masses

Look for the buff-coloured, spongy egg masses on the sheltered portions and crevices of items that are under or near trees. This includes all:

• outdoor equipment,
• outdoor furniture,
• outdoor toys and playground equipment,
• fences,
• tree trunks,
• wood and lumber piles,
• garden sheds and other gardening equipment,
• recreational vehicles (RVs, boats, trailers), and
• any other object that was stationary in the area during the months of July through August when the adults are reproducing.

Where to Find Larvae

Larvae hatch in early April and are found until late May. The young larvae are very small and difficult to identify. They feed at night and hide on the underside of leaves during the day. As the larvae get older and larger (they grow to about six to seven centimeters), they become more obvious and feed voraciously during both day and night.

Study the images of larvae found above and on the Gypsy Moth Biology page. There are many other caterpillars that feed during the same period as the gypsy moth which can lead to confusion and mis-identification. Gypsy moth are dark, hairy and have distinctive pairs of five blue and six red dots or tubercles on their backs (but sometimes they can be all black or blue).  Please be careful that you are not destroying rare or endangered butterfly caterpillars.

If you locate larvae, collect them in a tightly sealed plastic bag or jar and call the Canadian Food Inspection Agency at  (250) 363-3618 (Vancouver Island) or (604) 666-2408 (Lower Mainland/ Interior) for an inspector to identify them.

Wrapping a band of burlap or tar paper around the trunk of host trees can be used to trap larvae and pupae. The caterpillars seek shelter during the day and so can be found resting under these bands. At the end of the feeding period, many insects pupate in these shelters.

Where to Find Pupae

The pupal stage occurs between the end of the last larval stage and ends when the adult emerges. This period usually occurs from mid-July to mid-August. The gypsy moth caterpillars finds a sheltered location in which to pupate and are normally found next to or very near the egg masses. As noted above, pupae can often be found under tree bands.

The pupae are dark reddish brown, usually with a few yellowish hairs. You can easily tell male from female pupae as the female ones are much larger.

Where to Find Adults

Adults are present during the latter part of July and on through August. The male (a strong flier) is brown, with a small body and well-developed wings. The female is white with black markings on her wings, and much larger. Both male and female adults have a distinctive "chevron" marking on their wing. This marking is often difficult to see on moths caught in sticky traps and any suspect moth should be examined by a CFIA inspector. The male also has large, feathered antennae that it uses to smell the female pheromone.

Since the female does not fly, the adult female is usually found near the spot that she emerged from her pupal case. Unless consumed by other insects, her dead body is often located on or near the egg mass for an indefinite length of time.

The female attracts the male moth with a pheromone and then mates. Egg masses are usually laid nearby but the female can crawl a short distance into crevices and other sheltered locations which makes detection more difficult.

Adult male moths are readily attracted to sticky traps using a synthetic version of the female sex pheromone. These sticky traps are the key monitoring tool for estimating the abundance and occurrence of gypsy moth throughout North America.

Participation by homeowners in allowing traps to be hung on trees on their property facilitates the monitoring program and is greatly appreciated.

Gypsy Moth Homepage > Management Options > Description of the Eradication Strategy > monitoring > Selecting a Treatment > Aerial Spraying with Btk > Detailed Information on Aerial Spraying > Ground Spraying > Alternative Treatments > Public Involvement

Contact Tim Ebata if you have comments on the presentation of this information.

BC Ministry of Forests and Range
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2

Section phone: (250) 387-8739
Section fax: (250) 387-2136