Key Features
- Defoliation
- Holes in Leaves
- Worm-like hairy or hairless body
Symptoms
Caterpillars are the worm-like immature stages of butterflies and moths that can chew foliage, or feed on wood beneath the bark of a tree. They can be smooth or hairy, brightly or dull colored. They can completely consume leaves and defoliate plants. They are distinct from another groups of worm-like larvae called sawflies, a kind of plant eating wasp that cannot be killed by applications of a biological pesticide called Bacillus thuringiensis. Caterpillars are distinguished from sawflies by having 2-5 pairs of prolegs beyond the true legs. Each of these legs are capped with small barbs, called crochets. Sawflies have 6 or more pair of prolegs.
Biology
Caterpillars are the worm-like immature stages of butterflies and moths. This is the stage of moth that will defoliate trees, mine leaves, or bore beneath tree bark. Caterpillars do the most feeding and also are easiest to control. Eggs are usually laid as a mass that eventually hatches into small larvae that consume ever increasing large pieces of leaf. Depending on the species caterpillars, they usually have between 1-3 generations a year.
Management Recommendations
Most products are most effective when directed against small, young caterpillars. To prevent late season outbreaks of spider mites, early season caterpillars should be controlled with a biorational pesticides like the bacterium Bacillus thuringiensis, 'Kurstaki' (BT), spinosad (Conserve), chlorantraniliprole, azadirachtin, diflubenzuron,or tebufenozide. Other insecticides that work on later stage caterpillars include pyrethroids (bifenthrin, fluvalinate, permethrin, resmethrin) and carbaryl, and acetamiprid. To protect bees do not apply foliar insecticides when trees are flowering.
Effective Pesticides
Active Ingredients include: Azadirachtin, Bacillus thuringiensis var. Kurstaki, Bifenthrin, Carbaryl, Chlorantraniliprole, Cyfluthrin, Fluvalinate, Permethrin, Spinosad, Tebufenozide
