Spongy Moth (Lymantria Dispar)

Spongy Moth (Lymantria Dispar)

*UPDATE* The second and final aerial spray for 2022 will be conducted Tuesday, June 7 between 6am-7am.

In Summer 2021, an infestation of spongy moth (formerly known as gypsy moth) was discovered in Dee-Devon Woods, commonly referred to as Southwest Woods, the Forest Preserve property south of Devon Avenue between Dee Road and Western Avenue. Entire stands of trees were defoliated within a few short weeks as caterpillars fed on nearly every tree and shrub. While healthy trees can usually overcome one or two years of mild defoliation, trees that have been weakened by previous defoliation and other stressors are at a much higher risk of mortality.

2022 Aerial Treatment
To contain this outbreak and slow the spread of spongy moth, the city will be performing an aerial spray of the infested area in mid-May/early-June, weather pending, with a second application within the following two weeks. The aerial spraying will utilize a bacterium that, although harmless to humans, is effective in controlling the spongy moth in the caterpillar stage and is the safest and most selective method for reducing spongy moth populations. BtK is an organic, environmentally friendly alternative to chemical pesticides that has been used in the US since the 1960’s and approved by the U.S. Environmental Protection Agency, Health Canada, and the World Health Organization, among others. The product will be applied to the infested area via helicopter.


2022 Spongy Moth Aerial Treatment Map

A few days prior to the spray, signs will be placed along major collector streets in the treatment area and at main entrances to the Forest Preserve trails. Additionally, notice of the spray date will be posted on the city’s website. Although residential properties are not the target of this application, people who live or work near the application site may want to stay indoors for at least 10 minutes to allow time for the material to settle out of the air.

Residents should be aware that spongy moth is here to stay and has cyclically impacted Park Ridge’s urban forest since the 1980’s. Similar treatments were performed in the 1980’s and early 2000’s, both of which were effective in controlling the pest and improved resident satisfaction. While they cannot be eliminated, their population numbers can be controlled to a level acceptable for plant health and aesthetics. The City of Park Ridge Forestry Division will monitor spongy moth populations in subsequent years to see if applications will be warranted in the future.

What should I do about trees on my property?
Many local tree care companies can deliver safe and effective treatments for trees on private property. Tree-äge® is one product used by tree care professionals to control spongy moth and it is the same product we use to treat ash trees for emerald ash borer. The product is simply injected into the tree’s vascular system in the most effective and environmentally responsible way possible. As a preventative treatment, it can protect the entire canopy for a minimum of one year and should be applied in early spring.

For more information on this invasive insect and control programs, please visit the follow resources:
Illinois Department of Agriculture (IDA) - Lymantria Dispar/Spongy Moth
United States Department of Agriculture (USDA) - Gypsy Moth
National Slow the Spread Program

If you have any questions, or would like more detailed information, please contact the Park Ridge Forestry Division at 847-318-5231.