Tent Caterpillars: Control and Prevention

Know the Enemy

Tent caterpillars build conspicuous silken nests in branch crotches of trees and shrubs. By day they forage; by night they return. Heavy infestations can strip a tree bare.

Effective Non-Chemical Controls

• Prune nests at dusk: Cut off the infested limb when caterpillars are inside. Destroy the nest (burn, bag, or soak in soapy water).
• Break and spray: If pruning would disfigure the plant, tear open the nest with a stick and spray Bacillus thuringiensis (Bt) inside — caterpillars ingest it while feeding.
• Remove egg masses: In late winter/early spring, scrape off the shiny, varnished-looking egg bands from branches.
• Sticky trunk barriers: Wrap trunks with Tanglefoot or similar to block flightless females from climbing to lay eggs.

Chemical Options (Use Sparingly)

Carbaryl, diazinon, and malathion are labeled for caterpillars, but they also kill beneficials. Reserve for severe outbreaks where non-chemical methods have failed, and always follow label directions precisely.

Prevention Is Easier Than Cure

Scout in late winter for egg masses. Encourage birds and parasitic wasps — they're your best long-term allies.