How to deal with Spongy Moth around your property

Anelia’s Tree Corner

Interesting facts and tree care tips from certified arborist Anelia Tichkova

How to deal with Spongy Moth around your property

A new common name for Lymantria dispar, spongy moth, replaced the prior name of this insect, gypsy moth, in 2022. The Spongy moth is an invasive pest, native to Europe, that was introduced to North America accidentally in 1869 and has expanded its range over Eastern United States and Canada. It is now well established throughout southern Ontario and as far north as Sault Ste. Marie.

The spongy moth larvae or caterpillars will feed on a variety of deciduous tree leaves as soon as leaves appear in the spring. If the larvae population is high, they can defoliate whole trees and forests in a short amount of time. Repeated spongy moth outbreaks and defoliation of trees cause significant stress to trees, especially to oaks that are the most susceptible but highly valuable trees for sustaining healthy ecosystems. 

During the summer, the female moth lays eggs in masses of 100 to 1000 on tree bark, crevices, houses, fences, rocks, etc. The eggs are covered with fine light brown hairs. The egg masses will remain all winter and caterpillars will hatch in the spring, from late April to mid-May.

What you can do to protect trees on your property or neighbourhood?

• Homeowners are encouraged to monitor their hardwood trees like oak, birch, maple, beech, crabapple, basswood, willow and many other types of trees for the presence of larvae, or egg masses.
• Between the months of August and April, physically remove spongy moth egg masses. Use a putty knife or any other scrapping tool to gently remove the eggs into a container and destroy the eggs by leaving them in soapy water for several days.
• In the spring, wrap burlap bands at chest height, around trees. The caterpillars will crawl to seek shelter during the day. Use gloves to hand-pick caterpillars and crush or destroy by soaking in soapy water for 48 hours.
• Contact a professional tree care service provider if you believe manual removal is not sufficient.