Spongy Moth

LDDs, also known as Lymantria dispar dispar or gypsy moth, is an invasive insect found throughout southern Ontario that feeds on a variety of tree species such as oak, birch and maple. Originating from Europe, Asia and North Africa, LDD is now found in the eastern Canadian provinces. LDD caterpillars eat leaves causing the trees to lose some or in extreme cases, all of their canopy. However, since the canopy has the ability to regrow as the season progresses, long term effects can be reduced or prevented through management techniques.

This invasive insect was introduced to the United States in the late 1800s and was first detected in Ontario in 1969.

LDD's have four developmental stages. Due to the favourable climate for the LDD moth, the developmental stages for LDD moths have been accelerated by a month. 

1. Egg Mass Stage - Late August to early May 
2. Caterpillar Stage - Early May to mid-July 
3. Cocoon/Pupae Stage - Early to mid July 
4. Moth Stage - Mid July to mid August

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Yes, LDDs can be found in York Region and many large areas throughout the Province of Ontario.

LDDs are the most destructive in their larval stage as caterpillars as they will strip away foliage from a wide variety of trees by eating the leaves. Most healthy trees are able to regrow their leaves but some species such as oak species are very vulnerable to LDDs feedings. Over time, repeated defoliation will stress the tree which can kill it.

It is important to manage LDDs because they have the ability to deteriorate the health of the tree. The LDD caterpillars feed on the tree leaves and over time can cause the tree to lose all of its leaves. Most healthy trees are able to regrow their leaves but some species such as oak species are very vulnerable to repeated LDDs feedings and can be killed over several years. In addition, by managing LDDs on your property, you will help reduce the LDD population and its impacts on the environment in Newmarket.

Check for egg masses with caterpillars are oval in shape and normally have small black caterpillars around the egg sack like the photo below.

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Depending on the type of tree you have, the LDD caterpillars can cause defoliation to your tree. Most healthy trees are able to regrow their leaves but some species such as oak species are very vulnerable to repeated LDD feedings and can damage a tree over time. Trees that are in stress from other factors such as drought are more susceptible to die as they do not have the stored energy and/or vitality to grow another healthy crop of leaves. Watering and fertilizing a defoliated tree will help the tree overcome the strain of growing another set of leaves. Currently, the Town's tree canopy has begun to show signs of regrowth and are recovering from LDD caterpillar feedings.

LLD caterpillars will eat the leaves of a variety of trees but oak species are generally targeted.

The Town of Newmarket's forestry department is currently identifying 'hot-spots' and priority Town-owned areas that are prone to LDD feedings and monitoring the LDD population while working with York Region on best practices on controlling the LDD population. In the spring, the Town set up burlap bands to trap the LDD caterpillars in priority areas on Town property. This fall, the Town will be removing LDD egg masses with backpack vacuums in areas with trees that are vulnerable to LDD feedings. Trees selected for egg mass removal will be marked with a white dot.

The Town will not be spraying LDD with pesticides at this time due to the reduction in effectiveness of the spray during this stage of the lifecycle for the LDD caterpillar. In addition, more data collection about the LDD population is required before the decision to spray can occur. Spraying not only kills the LDD caterpillars but all caterpillars that may be a food source for other wildlife.

Trees located on private property are the responsibility of the homeowner. If you need additional assistance on caring for your tree, we recommend you contact a tree care specialist. The Town of Newmarket does not treat/manage trees on private property, however there are some steps residents can take to protect their trees from LDDs.

August to April and August to December
Scrape and destroy egg masses. You can do this by scraping egg masses off trees and placing them in a bucket of soap water for a day or two. Please wear gloves while doing this work as the caterpillars can irritate your skin.

April to June
Consider applying insecticide such as BTK or Tree Azin – both insecticides are not harmful to people or the environment. Many products have a tight window in order for the application to be successful. We recommend you contact a licensed tree care company to learn about your options to manage LDD.

May to August
Use burlap bands to trap LDD caterpillars. Wrap a 45cm piece of the burlap entirely around the tree's trunk at chest height to catch the caterpillars. Tie a piece of string half-way up the burlap and fold the top section down over the string to create a skirt. This trap should be checked daily and any captured caterpillars should be removed and placed in a container of soapy water for a day or two before being disposed of. Please wear gloves while doing this work as the caterpillars can irritate your skin.

June to July
During this time, you can handpick the caterpillars and place them in a bucket of soapy water for a day or two. Please wear gloves while doing this work as the caterpillars can irritate your skin.

The Town of Newmarket will not be spraying LDD caterpillars at this time because the effectiveness of spraying is reduced during this lifecycle of LDD. In addition, more data collection about the LDD population is required before the decision to spray can occur. Spraying not only kills the LDD caterpillars but all caterpillars that may be a food source for other wildlife. At this time in the season, burlap traps are the most effective way for residents to trap LDD caterpillars on their property. We will continue to work with York Region and local municipalities on best practices in managing LDD in our community.

Unfortunately, the Town does not have the capacity to take requests to remove egg masses in specific areas in Newmarket. The Town will be using the data collected in the above map to identify trees which are vulnerable to LDD feedings and focus on removing egg masses from them. Trees that are vulnerable to LDD feedings and will have LDD egg masses removed from them will be marked with a white dot.