Mimosa Webworm on Mature Honey Locusts: Treatment Timing and Options

Two 38-foot honey locusts treated for webworm 8 years. Owner wants to know if height eliminates risk and if treatment can stop.

Facts

• No height immunity—webworms attack at any height.
• Two generations/year: June and August.
• Population varies yearly; some years minimal.

Treatment Protocol

• Spray early June and August for best control.
• Rake/destroy fallen leaves to reduce overwintering population.
• Labeled insecticides: acephate, azadirachtin, Bt, bifenthrin, carbaryl, chlorpyrifos, cyfluthrin, deltamethrin, diflubenzuron, lambda-cyhalothrin, permethrin, spinosad, etc.

Resource

PSU Mimosa Webworm Fact Sheet