The last two years residents of Southern Ontario have had to live with an unwelcome guest in our backyards, parks, playgrounds and cottages. Gypsy Moths

Not only do these menacing insects rain down excrement produced by them feeding on the leaves of trees, covering cars, patio furniture and decks but it also is detrimental to the health of your trees. Luckily, gypsy moth caterpillars only feed for four to six weeks, ending around early or mid July when they will cocoon, pupate and emerge as an adult moth. Soon after mating, females will lay eggs and die.

While in caterpillar form, your trees can be completely defoliated, but most will recover and generate more foliage. In this article I will give you the information on protecting your trees during the unwanted invasion from these crawling plunderers. 

First it is important to identify the gyps moth caterpillar. A lot of different insects feed on foliage and you want to ensure you are dealing with a gypsy moth. These caterpillars are dark, almost black in colour, they have six pairs of red spots, five pairs of blue spots down their backs and are about 2 inches in length.


  • WATER – If your trees have received significant defoliation from caterpillars, ensuring that your trees receive plenty of water will help regrowth. Providing at least one inch of water, at minimum once per week, either from rain or watering is important to help trees recover. This can be achieved by running a sprinkler under the trees spread for about one hour in the evenings.
  • SOAPY WATER – Spraying the trees with a strong mixture of soapy water will help remove caterpillars. Be sure to spray the underside of leaves. This won’t kill them but it will cause them to drop off and they can then be placed in a bucket of soapy water for 24-48 hours. This will reduce the population for the following year.
  • REMOVING EGG NESTS – Once the adult gypsy moth emerges from their cocoon they will enter a meeting cycle. The female will produce a tan coloured egg mass that could have as many as 200 eggs. By removing these egg masses you can reduce the population for future years. Simply remove the egg mass and soak in soapy water for 24 to 48 hours, just removing them onto the ground will not kill the eggs, they will still be able to hatch the following year.
  • BURLAP BANDS – Individual trees can be protected by wrapping 12 inch burlap bands around tree trunks and secure from movement. During the daytime, caterpillars will take cover under the burlap, remove the burlap and knock the caterpillars off into a bucket of soapy water for 24-48 hours.
  • STICKY TAPE – Bands of sticky tape such as duct tape installed around the tree trunk can be effective in keeping caterpillars from reaching the foliage on your trees. Install 4 bands of inside out duct tape type material around the trunk of your tree to capture caterpillars.
  • INSECTICIDES The use of insecticides can be quite effective although it is recommended to contact the company that has the experience in dealing with such chemicals. Proper equipment, experience and application is important to control the insects you are targeting. There are many different types of products available to homeowners for use on their property. Be sure to read the label for the proper application, safe instructions and recommended PPE. Use of broad-spectrum chemical pesticides  pose a danger to insects that support your backyard ecosystem and are not recommended. If you are thinking about using insecticides it is recommended to contact a professional.

Overall it is best not to panic. Healthy trees can handle defoliation and still produce leaves following spring as normal. Young trees or trees in a vulnerable state will have a harder time with defoliation but by paying attention to your trees, keeping them well watered and fertilized they will last through this infestation into the next season.