2025 Spongy Moth Spray
Notice of Spring Treatment and Public Hearings
In response to resident requests, the City of Wyoming has a long-standing practice of providing spongy moth monitoring and a spring treatment as needed. The following is a tentative schedule based on past practices:
March 17, 2025: A public hearing was held as part of the regular City Council meeting. During this meeting, the City Council received public comment from persons affected by the proposed spongy moth project and the associated special assessment. The notices below were mailed to all property owners in the treatment area to notify them of the public hearing. The notice describes the project, the process, and how to provide public comment.
Following public comment at the March 17 meeting, the City Council decided to proceed with the spongy moth treatment and special assessment process.
April 7, 2025: A second public hearing was held as part of the regular City Council meeting. During this meeting, no members of the public provided comment on the proposed spongy moth project or the special assessment. The notices below were mailed to all property owners in the treatment area to notify them of the public hearing and how to provide public comment.
Following public comment at the April 7 meeting, the City Council confirmed the spongy moth suppression program and the special assessment. The City Council also approved an agreement with an aerial applicator at this meeting.
2025 Treatment Locations
Using resident complaints, tree damage assessments and egg mass surveys, our consultant, Aquatic Consulting Services, LLC, determines the areas of treatment. A total of 399 acres have been identified for treatment this year. You can find treatment locations on the Aerial Spray Map 2025 (PDF) or use the Interactive, Searchable Spongy Moth Map.
Property Owner Cost
If a property you own is within a treatment location, a fee is assessed on your 2023 Summer property tax bill. The fees will be as follows:
- $30 for small parcels or treatment areas equal to or less than .5 acres
- $93 per treated acre for parcels with treatment areas larger than .5 acres
How It Works
In addition to working with Aquatic Consulting Services, we partner with Hamilton Helicopters, Inc. to perform spongy moth treatment in the springtime. The exact spray date is determined through continued monitoring of weather conditions, as well as caterpillar and tree canopy development. Spraying will be done when average wind speed is less than 10 miles per hour and relative humidity is more than 50-percent. In most cases, this limits spraying to a morning activity.
The insecticide used in this process is a naturally occurring bacteria called Bacillus thuringiensis (Bt), which is also used by organic gardeners. The Bt brand used is Foray 76B (or equivalent). On treatment days, our contractor will apply 1 quart of the Bt material over each acre in a very fine mist. It is unlikely for people to see or feel it. Application generally takes 2 - 4 hours (for the entire city) and the product dries within minutes.
The Bt only affects the caterpillars of moths and butterflies that are actively feeding at the time of treatment, which is why the application date varies. In an effective spray application, you may notice a change in the level of activity and responsiveness of the caterpillars, and they will die in 5-7 days.