2026 Spongy Moth Spray
Notice of Spring Treatment and Public Hearings
In response to resident requests and damaging infestations, the City of Wyoming has a long-standing practice of providing spongy moth monitoring and a spring treatment as needed.
Public hearings were held on March 16 and April 6, 2026, to allow persons affected by the proposed spongy moth project and the associated special assessment. Notices were mailed to all property owners in the treatment area to notify them of these public hearings. The notice described the project, the process, and how to provide public comment.
Following public comment at these meetings, the City Council approved the special assessment and related materials and treatment is now tentatively scheduled for mid-May. Determining an exact treatment date is very challenging and is very dependent on weather conditions.
2026 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 205 acres have been identified for treatment this year. You can find treatment locations on the Aerial Spray Map 2026 (PDF) or use the Interactive, Searchable Spongy Moth Map.
Property Owner Cost
If you own property within a treatment area, a fee will appear on your 2026 Summer property tax bill. The fees will be as follows:
- $38 for small parcels or treatment areas that total less than .5 acres
- $117 per treated acre for parcels with treatment areas equal to or 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.