LDD Moth (Lymantria dispar dispar) (also known as gypsy moth)

Please note

In our efforts to lead an inclusive organization, we will be transitioning away from the use of “gypsy moth” and will be using the term “LDD moth” going forward.

 

Facts

LDD moths (Lymantria dispar dispar) were originally imported to Boston from Europe as a potential silk producer. Unfortunately, they escaped and have been in Ontario for approximately 60 years. The first major outbreak in Ontario was in 1985.

Caterpillars start to emerge from egg masses in mid-to-late May and will spend about 40 days eating all the leaves or needles that they can consume.

LDD caterpillars prefer to eat oak but will eat many other species such as maple, poplar, cherry, willow, birch and spruce.

Each caterpillar will eat about one square metre of leaf material before cocooning for 10 to 14 days.

Adult moths emerge from cocoons in June – July to focus solely on breeding and egg laying. They don’t eat at all during this stage and live for approximately two weeks.

LDD females usually lay between 100 to 1,000 eggs.

They don’t create ‘tents’ like some other species such as fall webworm or eastern tent caterpillar.

Unlike the devastation caused by emerald ash borer (EAB), LDD moth outbreaks rarely cause damage to forests on a large scale.

For more information on the history, dispersal and management of LDD, view this video.

Frequently Asked Questions

Will LDD moths kill my trees?

Healthy trees can typically survive three to five years of heavy moth feeding. A healthy tree will usually be able to regrow their leaves later in the season. However, if the trees are stressed due to drought, disease, fungi or other insects, this loss of leaves can deplete the tree’s energy reserves and eventually result in death. Unfortunately, conifer trees (though not the moth’s favourite meal) can die after only one year of very heavy feeding.

Does anything eat the LDD moth?

Several local species will eat the caterpillars or pupae. Birds such as blue jays and orioles will eat the caterpillars, and chickadees will feed on the egg masses. Mice, chipmunks, skunks, voles and other small mammals will eat the pupae or larvae.

How long will a heavy infestation last?

These outbreaks occur every 5-10 years and usually last between two and four seasons. Outbreaks generally collapse due to the combined effects of natural controls: a fungus (Entomophaga maimaiga), a virus (Ld-Nucleopolyhedral virus), and parasitic wasps and flies. The effectiveness of these natural enemies is dependent on weather conditions and the size of LDD moth populations.

What can I do on my property?

Please note: the hairs on LDD moth caterpillars and in egg masses can cause irritation or allergic reactions in some people. Consider using gloves and other protective wear whenever contact is possible.

There are several ways that you can try to help a tree affected by this moth. Usually a combination of these methods works best. You won’t get rid of all the caterpillars, but you can reduce the amount of damage they cause. If there are a few trees on your property that you’re concerned about you can concentrate your efforts on them. If you have a larger woodlot some damage to a few trees is not likely to have a big effect on the forest in the long run.

If you’re worried about the trees on your property you can try the methods listed below or consult a local tree service company.

Action Description Time of Year
Keeping your tree healthy This can mean watering in dry periods, adding mulch to the soil around its base and making sure its root zone is clear of heavy objects or things preventing rain from getting into the soil. Year-round
Egg mass scraping

Until the tiny caterpillars start emerging in May, the oval-shaped, tan-coloured egg masses can be scraped off trees and other surfaces into a container. Fill the container with soapy water, and make sure you stir the egg masses and break them up if possible. Let them sit for two days in a sealed container to kill the eggs and then put them in the garbage. Scraping egg masses onto the ground will not kill them.

LDD moth egg masses can be found on almost any surface, including the side of your house.

View this video for more information.

August – early May
Trunk wrapping

When the caterpillars are present various forms of wrap can be used on the trunks of trees to catch and dispose of caterpillars. Double-sided sticky tape can catch caterpillars as they walk across it. There are some products available at garden centres which are specifically designed for this purpose. You can also wrap a wide strip of burlap around the trunk, tie it around the middle with string and then fold down the top to create a sort of pocket. Caterpillars will gather there for shelter during the day and they can be routinely caught and disposed of.

View this video for more information.

May – July
Hand picking caterpillars Collect caterpillars from trees or other surfaces into soapy water and make sure the solution is well mixed. And then discard them in the garbage. Wear gloves to ensure your skin is not irritated by the caterpillar hairs. May- July
Spraying Btk

Btk (Bacillus thuringiensis kurstaki) is a biopesticide that can kill moths in the caterpillar stage when sprayed on the leaves of affected trees. The caterpillar needs to eat the bacteria off the leaf to be killed. Various Btk products are publicly available, however it should be applied by a registered pesticide applicator. This can be done through ground sprays or aerial sprays for larger forested areas. Consult a local tree service company for ground spray options and research for aerial spray options well in advance of the spring season.

Note: Pesticides of any kind should only be used with the greatest caution. Always make sure to carefully read the label and follow instructions for the proper timing and dosage of application. Visit Health Canada to read about the safety of Btk. This spraying can be done for individual trees or for large scale infestations.

Planning: winter before you want to spray

Spraying: May – June

Set out pheromone traps Pheromone traps can be used to attract and trap adult male LDD moths to stop them from mating with females. Although this is generally used in monitoring LDD moth populations, it can reduce egg mass loading in small areas. July – August

Gypsy moth egg masses can be found on almost any surface, including the side of your house.

LDD moth egg masses can be found on almost any surface, including the side of your house.

What is CVC doing?

There are many invasive species in our watershed and we’re currently focusing our efforts on the ones that have the potential to cause the most damage to our ecosystems. For this and other reasons we’re not actively managing LDD moth on our properties at this time.
However, we are doing the following:

  • Developing an Integrated Pest Management framework based on the latest research which will include a LDD moth monitoring program for our properties.
  • Working with our partners to increase collaboration and formalization of watershed initiatives.
CVC is pleased to provide, in partnership with TRCA, a free information webinar on June 8 on the LDD moth (European gypsy moth). Webinar participants will learn about the LDD moth life cycle, how to identify them and what actions you can take to minimize their impact to trees. Registration is full. A recording of the webinar will be posted soon. 

CVC is happy to provide information and education about management techniques, as described above. If you have questions, please contact us at invasivespecies@cvc.ca

For further information on LDD Moth, visit the Invasive Species Centre or Ministry of Natural Resources and Forestry.

X
COVID-19 related service changes
Data and information released from Credit Valley Conservation (CVC) are provided on an 'AS IS' basis, without warranty of any kind, including without limitation the warranties of merchantability, fitness for a particular purpose and non-infringement.

Availability of this data and information does not constitute scientific publication. Data and/or information may contain errors or be incomplete. CVC and its employees make no representation or warranty, express or implied, including without limitation any warranties of merchantability or fitness for a particular purpose or warranties as to the identity or ownership of data or information, the quality, accuracy or completeness of data or information, or that the use of such data or information will not infringe any patent, intellectual property or proprietary rights of any party. CVC shall not be liable for any claim for any loss, harm, illness or other damage or injury arising from access to or use of data or information, including without limitation any direct, indirect, incidental, exemplary, special or consequential damages, even if advised of the possibility of such damages.

In accordance with scientific standards, appropriate acknowledgment of CVC should be made in any publications or other disclosures concerning data or information made available by CVC.
DATA DISCLAIMER