Preventive control of the forest tent caterpillar

Apr 20, 2026

Summer is just around the corner! Very soon, the trees will be full of leaves. Before the leaves burst open, it's the perfect time to inspect the small trees around your home and remove any forest tent caterpillar eggs!

For the past three years, forest tent caterpillars (Malacosoma disstria) have infested some deciduous trees in our community, causing significant damage to the foliage and inconvenience for residents. Fortunately, trees have reserves and can regrow leaves during the summer. However, if a tree is repeatedly defoliated over several years, it could suffer irreversible damage and eventually die. The good news: it's possible to take preventative action to limit the appearance of forest tent caterpillars in your area.

At the start of the season, before the eggs hatch and the leaves begin to bud, you can take easy and effective action. Here are a few tips.

How to spot the eggs?

• They appear as small brownish-gray sleeves, attached around young shoots.
• They are found mainly on trees such as poplars, birches, cherry trees, apple trees, maples, etc.
• These eggs were laid at the end of last summer, overwintered, and are ready to hatch in the spring.

How to remove them?

• Inspect your trees, especially branches at head height.
• Scrape or cut away the branches by bearing the eggs using a tool (knife, pruning shears).
• Immerse the eggs in a bucket of soapy water for about 24 hours.
• Avoid leaving the eggs on the ground, as the caterpillars could still hatch.

Safety tips:

• Wear gloves, even if the eggs are not stinging.
• Once hatched, the caterpillars can cause skin reactions in some people.

Why act now?

• You protect your trees from premature defoliation.
• You reduce the spread to your neighborhood.
• You limit the nuisance caused by stinging caterpillars later in the season.

Things to avoid

Please do not put sticky tape on the tree trunk. This method is ineffective in most cases and risks damaging the tree.

• Upon hatching, the caterpillars are already inside the trees.
• A large proportion of the caterpillars are dispersed on silken threads carried by the wind. Many therefore colonize neighboring trees without leaving the ground.
• Sticky tape on the tree trunk poses several risks, including tissue asphyxiation, cambial burns, and bark damage.

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CONTACT : Daniel Gautreau, Coordonnateur aux espaces verts, Service des travaux publics, 506.739.2103, daniel.gautreau@edmundston.ca