Spongy moth is an invasive insect also known as “LDD moth” (Its latin name is Lymantria dispar dispar. It also used to be called “gypsy moth”.) It’s been in Ontario since 1969. Click here to see a fact sheet about spongy moths.
As caterpillars, they eat the leaves of trees (they like oak, birch and aspen) and often damage or kill the tree. Outbreaks of moths are cyclical, typically occurring every 7-10 years, with an outbreak lasting 3-5 years. Forestry Services predict that 2022 will be bad year for spongy months.
How to protect your trees:
May to September:
Place burlap around the trunks of your trees: During this time, the fully-grown caterpillars move down the tree trunks. If a tree has burlap, they hide in it. Check it every afternoon and remove any caterpillars (with gloves! their hairs can irritate) and drop them into soapy water for 24 hours to kill them. Then compost them. Click here to see a fact sheet on burlapping trees.
May to June:
Apply Btk biopesticide to trees: Btk (Bacillus thuringiensis kurstaki) is a biopesticide availableat local hardware stores. It affects the caterpillars’ digestive system. Only use it between May and early June when spongy moths are still in the larval (caterpillar) stage.
May to July:
Hand pick caterpillars: This is most effective on small, newly-planted trees, shrubs, and plants infested with spongy moth. If possible, first gently shake the tree so that the caterpillars fall from leaves. Thoroughly inspect the remaining foliage, branches, and trunk for caterpillars. Wearing gloves, pick them off your tree. Again, put them in soapy water for 24 hours.
August to May:
Egg mass removal: Now you know what they are called “spongy moths” — the egg masses look spongy. Survey your property for egg masses on trees and other surfaces and scrape them off into soapy water for 24 hours to destroy them. Click here to see a fact sheet about egg mass removal.
Report sightings: At any time of the year, you can report spongy moth sightings to the City of Ottawa using the online reporting tool.