Tent caterpillars
Hairy social caterpillars that build white silk nests in the forks of branches in spring and strip the leaves from fruit and ornamental trees.
Also known as: Eastern tent caterpillar, Lackey moth caterpillar
Symptoms and identification
Silky white tents appear in the forks of branches in early spring, and groups of striped, hairy caterpillars leave them to feed on leaves. Branches can be stripped bare, and black droppings fall below the tree.
Causes
Egg masses on twigs hatch as the leaves unfurl in spring. The caterpillars feed for 4 to 6 weeks, then leave to pupate. Trees usually regrow leaves and survive one defoliation.
Organic treatment
Remove tents by hand early in the morning or evening when caterpillars are inside, and drop them into soapy water. Spray Bacillus thuringiensis (Bt) on foliage where young caterpillars feed.
Prevention
Prune out and destroy the shiny, foamy egg bands on twigs in winter, and keep an eye on fruit trees in early spring.
Chemical treatment (use with care)
Use an insecticide labelled for tent caterpillars, sprayed on young caterpillars in spring, following the label.