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LDD/Spongy Moth

 In 2021, the Entomological Society of America changed the name "Gypsy Moth" to "Spongy Moth" due to the changing regulatory landscape preventing insect names that reference other ethnicities or races. The new name reflects the light brown color and spongy appearance of the egg masses they produce. There are two variants, the European LDD Moth, and the Asian LDD Moth. Both variants are not native to North America and are classified as invasive species regulated by the Canada Food Inspection Agency. As the European Spongy Moth is the species found in Eastern Canada, we will concentrate on information on this species.

The LLD moth was introduced into North America by a misguided scientist who thought he could breed the LLD Moth with the native Silk Worm to establish a silk industry in the USA. That did not happen, but the Spongy Moth was allowed to escape from the laboratory in Massachusetts, where the moth became established. Since that initial escape, the LDD Moth has spread throughout the Northeast USA and from Ontario east to Nova Scotia.

That escape occurred in 1870 and as the moth is not native here, there are insufficient natural controls to keep populations in check. Our MNRF will tell you that the LDD Moth is now just a part of our natural environment as are the Spruce Budworm and Forest Tent Caterpillar. Genetics move along at a very slow pace so any controls that we develop to keep these introduced pests naturally in check will probably take thousands of years, not 150. In the interim LDD, populations will increase to outbreak levels on a somewhat predictable basis and remain high for up to 4 years allowing substantial damage to occur.

Populations will fall on their own eventually when a virus and/or a fungus collapse the population. I will leave the technical names unnamed as they have little value to the average individual looking for LDD Moth control measures.

Life Cycle

The LDD moth overwinters as eggs and hatch out in the spring. These egg masses are laid just about anywhere, which is why it was called the Gypsy Moth. That included vehicles, campers, firewood, not just preferred host trees. This allowed them to expand their territory with each passing year.

Once hatched the larvae will climb to the crowns of the host trees and feed. This will occur continuously until the larvae mature and pupate. Typically, that is early July but can vary due to location and weather considerations.

In late July, early August the adult moths will emerge with the sole goal to mate for a period after which they die. The female does not fly so you do not have to search too far to see egg masses. Egg masses will be laid on tree trunks, road signs, houses, woodpiles, playground equipment, and the crotches of trees, to name a few. This is not to say that all egg masses will be low and easily accessed. Even though the female does not fly, she finds a way of getting up into the tree and will lay eggs where you simply cannot see or have access to remove them.

A female in a heathy and growing outbreak may lay up to five hundred eggs in a single egg mass. From here, the cycle begins to repeat until populations wane or collapse.



The Ontario Centre for Forest Defoliator Management is a private company resource that deals with LDD (Spongy Moth) outbreaks, as well as other forest defoliators such as the Forest Tent Caterpillar and, Hemlock Looper. It has become clear that most municipalities do not want to be offering pest control services for private property, and the Ontario MNRF have taken the do-nothing approach, the pest will go away on its own when the cycle ends.

Our team of experts, originating from Zimmer Air Services Inc. has been actively engaged in the delivery of private programs to the individual, cottage association, maple syrup producer since the introduction of btk products in Canada in the early 1980’s.

Because these pest outbreaks are not constantly present the need for this service may go from non-existent in one year, to overwhelming demand the next. This has placed an unsustainable workload on the staff of aerial application companies which is why there is very little interest from them. Zimmer Air Services Inc. continued to offer the service; however, this did reduce their ability to address the needs of their regular business clients which they need to service to ensure the company’s success and survivability allowing them to offer this service to the public on the sporadic basis of pest outbreaks which may be only once every several years.

Although our primary focus is in the Province of Ontario we are capable and have delivered effective control programs out of province if deemed appropriate.

The role of the Ontario Centre for Forest Defoliator Control is to offer the setup and execution of effective and affordable aerial application programs.

Should you wish to obtain more information on a control program please review the wealth of information on this website. We have an information request form attached. Fill it out and someone will get back to you.

We also have a Toll-Free number to call, however you may need to leave a message and wait for a return call. This line will not be staffed at all times but will be monitored daily during the business week.

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Control Measures

Fact sheets and additional links found here provide a substantial amount of information to help you deal with this pest. They include egg mass removal, banding, tree injection, ground pesticide applications, and of course Aerial Application which has proven to be quite effective at reducing larval numbers at a reasonable cost.

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