Gypsy Moth infestations can cause moderate to severe defoliation of certain types of trees. Healthy trees can usually withstand losing their leaves for a few years. However, several years of defoliation can severely weaken or kill trees.
The European Gypsy Moth is a non-native insect that was introduced to North America in 1869. The caterpillar or larva stage of the Gypsy Moth eats the leaves of trees; this causes the trees to be more vulnerable to disease and attack from other insects.
Control Methods for Homeowners and Residents
- Conservation Halton urges all residents to participate in the control program by scraping and destroying egg masses, and catching and destroying caterpillars;
- Your choice of control method will be closely linked to the Gypsy Moth’s stage of development, as described by season below.
September to late April: Remove and destroy egg masses
- The Gypsy Moth is in the egg stage between early September and late April. Egg masses can be found on tree trunks, branches, buildings, and objects around the house;
- One egg mass contains about 300 eggs. By destroying them you will significantly reduce the number of caterpillars that emerge in the spring;
- Place collected egg masses in soapy water for a few days and then discard them in the garbage;
- Scrape off egg masses with a dull knife. If they fall on the ground crush them with your shoe;
- Egg masses are easy to vacuum off trees, buildings, and other objects with a portable or a household vacuum cleaner. Reach egg masses that are located at higher elevations on the tree by adding a number of extension pipes to the vacuum hose, or with the help of a ladder.
Late April to early May: Place sticky barriers or bands on the tree trunk
- Wrap duct tape around the tree trunk and apply a thin coat of sticky material (ready-to-use products are commercially available in most garden centres) to the duct tape. This prevents young caterpillars from crawling up the tree;
- Doing this will effectively trap only young caterpillars that are already crawling on trees or that emerge from egg masses that are situated low on a tree trunk or on other buildings and objects.
Late May to August: Replace sticky bands with burlap bands
- Caterpillars feed at night and hide during the day in shelters that protect them from the heat;
- Trap and destroy caterpillars by placing burlap (cloth) bands on trees;
- Wrap burlap that is approximately one metre wide around the tree trunk, tie it at the middle with a rope, and fold the burlap over; caterpillars will congregate under the burlap;
- Destroy caterpillars that emerge from under the burlap late in the afternoon before they crawl back to the canopy to feed.