Lymantria dispar dispar - European Gypsy Moth (LDD)

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Municipal Office

395 Mulock Drive P.O. Box 328 Station Main, Newmarket, Ontario
L3Y 4X7
905-895-5193

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Lymantria dispar dispar (LDD) also known as the Gypsy Moth, is an invasive insect that has been found in the Town of  Newmarket. LLD caterpillars will eat the leaves of a variety of trees but oak species are generally targeted. Most healthy trees can withstand one to several years of defoliation by LDD as healthy trees are able to regrow their leaves during the same growing season within two to three weeks. The LDD moth population generally surges every 7 to 10 years and the increase usually lasts for 1 to 3 years. Newmarket is currently at the beginning of the pupae/cocoon/LDD moth phase and the Town's tree canopy has begun to show signs of regrowth and are recovering from LDD caterpillar feedings. 

What is the Town doing to treat LDDs?

The Town of Newmarket's forestry department is currently identifying 'hot-spots' and priority Town-owned areas that have egg masses while working with York Region on best practices on controlling the LDD population. The Town has begun to remove burplap traps in preparation for the next phase of the LDD moth lifecycle as the LDD moth is currently inbetween the pupae/cocoon and moth phase. 

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. During the caterpillar phase, burlap traps are the most effective way for residents to treat LDD on their private property. As the LDD moth is currently in the pupae/cocoon stage, residents can remove burlap traps from their trees and keep them for use next season. 

We will continue to work with York Region and local municipalities on best practices in managing LDD in our community. Please note that the Town does not treat LDD on private property. Residents are encouraged to contact an ISA Arborist if they are considering applying insecticide to their trees. 

While LDD caterpillars may have been unpleasant, and cause trees to lose their leaves, the majority of trees will be able to withstand many years of defoliation by LDD and be able to regrow their leaves without significantly damaging the tree's heath. Currently, the Town's tree canopy has begun to show signs of regrowth and are recovering from LDD caterpillar feedings. 

Tree with leaves  Tree brach with leaves


What can I do to protect trees on my property?

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. Due to the favourable climate for the LDD moth, the developmental stages for LDD moths have been accelerated by a month. As the LDD moth is currently in the pupae/cocoon stage, residents can remove their burlap traps and any kind of trap from their trees and keep them for use next season. 

Mid July (current year) to April (following year) 

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 early July 

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/pupae/cocoon and place them in a bucket of soapy water for a day or two. Please wear gloves while doing this work as the caterpillars/pupae/cocoon can irritate your skin. 


Life Cycle of LDD

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 (Current Stage) 
  4. Moth Stage - Mid July to mid August
LDD Moths in Pupae/Cocoon Phase
Photo of the LDD moths currently in the pupae/cocoon phase. 
Lifecycle of Lymantria Dispar Dispar.png

Graphic courtesy of York Region.

Report LDD sightings in your neighbourhood 

Moth laying eggs on tree

We are currently collecting LDD egg mass information. LDD egg masses are fuzzy, a tan colour and range in size from a dime to a larger toonie. The egg masses are laid individually or in a large clump. If you see egg masses in your neighbourhood, report it to the Town of Newmarket using this online form. Data collected will help the Town identify hot-spot areas, identify how vast the LDD population is in the community and help to develop strategies for next year to mitigate the negative effects of LDD. See the map below for LDD hotspots in Newmarket.


Frequently Asked Questions 

What is Lymantria dispar dispar?

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. 

Where did LDDs come from?
This invasive insect was introduced to the United States in the late 1800s and was first detected in Ontario in 1969.
Do LDDs exist anywhere else?
Yes, LDDs can be found in York Region and many large areas throughout the Province of Ontario.
Why are LDDs harmful?
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. 
Why is it important to manage LDDs on my tree on private property?
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.
How can I identify that I have LDDs on my tree?
Check for egg masses with caterpillars are oval in shape and normally have small black caterpillars around the egg sack.
Will LDD harm my tree?
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. 
What types of trees will the LDD affect the most?
LLD caterpillars will eat the leaves of a variety of trees but oak species are generally targeted.
What is the Town doing to manage LDDs?

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. The Town has also set up burlap bands to trap the LDD caterpillars in priority areas on Town property.

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. At this time, burlap traps are the most effective way for residents to treat LDD on their private property. 

Why won’t the Town treat/manage my tree located on private property?
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. 

Why isn't the Town spraying LDD caterpillars?
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. 

Use of the name Lymantria dispar dispar (LDD)  

Lymantria dispar dispar is more commonly known as gypsy moth. However, use of the name gypsy moth could be perceived as culturally insensitive. As part of Newmarket's commitment to Diversity, Equity and Inclusion by promoting equity, accessibility, and inclusion through our thoughts and actions in support of our growing community, the Town will be replacing the name gypsy moth and introducing the Latin name Lymantria dispar dispar (LDD) in our communications. 

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