Spongy Moth Aerial Treatment

The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) uses aerial treatments to slow the spread of spongy moth (Lymantria dispar) in western Wisconsin as part of the National Slow the Spread program. To learn more about this invasive species and its negative impacts, visit spongymoth.wi.gov.  

Treatment Locations and Timing

Review the interactive map to learn where treatments will occur this year. Upcoming treatment dates will not be available until a day or two ahead of schedule because success is dependent on spongy moth caterpillar growth and favorable weather conditions. 

Aerial treatments usually occur in the morning when weather conditions are more likely to be optimal (high humidity and low winds) to prevent product evaporation or drift from the application site, but planes may fly later into the day if work remains to be done and weather conditions remain favorable. Small yellow planes will be heard and seen flying very low to treat treetops where the caterpillars are feeding. ​

Treatment Plan Notifications and Updates 

Treatment plan notifications and updates include: ​

• Open-house style public meetings are held in the regions where treatment will occur. In 2026, four meetings are scheduled:
  

  ​​Location	​Address	​Date	​Time​
  ​Platteville Public Library	​225 W. Main St., Platteville​	​Monday, March 9​	​5-6:45 p.m.​
  ​Arcadia Public Library	​730 Raider Drive, Suite 3140, Arcadia	​Tuesday, March 10	​4-6 p.m.
  ​Spooner DNR Service Center	​810 W. Maple St., Spooner	​Wednesday, March 11	​11 a.m.-1 p.m.
  ​Boyceville Public Library	​903 Main St., Boyceville	​Wednesday, March 11	​5-7 p.m.

  
  
• Postcards are sent to residents within or near treatment areas about one to two weeks before public meetings and one to two weeks before treatments are estimated to begin
• County and municipal officials are notified via email that spray sites are within or near their jurisdiction in early spring.
  
• A press release is sent out to the media approximately one to two weeks before public meetings, which is about two months ahead of treatment; and again at least one to two weeks before treatments are estimated to begin.
• Emails are sent one to two days before treatments (sign-up to receive email updates)
  
• Social media posts are sent out one to two days before treatments on:
  
• Facebook: facebook.com/widatcp​
• Instagram: instagram.com/wisdatcp
  

• X: x.com/widatcp​​​​
  

• ​A pre-recorded message with upcoming treatment plans is available 1-2 days before each treatment on the Spongy Moth Hotline: (800) 642-6684, menu option 1​​​​
  

​Products

Two different products may be applied aerially in the Slow the Spread program, Foray® 48B and SPLAT GM-O™. Foray 48B is an organic product that utilizes a natural soil bacteria, Bacillus thuringiensis kurstaki (Btk)​, which only impacts caterpillars that ingest treated leaves and biodegrades within days. This product is typically used in areas suspected to have a denser spongy moth population. SPLAT is an organic mating disruptor containing a spongy moth-specific pheromone imbedded in wax droplets which prevent male moths from finding females. This product is only used in areas with low-moderate density spongy moth populations.​​​​

Treatment Area Selection​

Traps are set in a grid pattern during the summer to identify outlier populations in western Wisconsin where spongy moth hasn't otherwise established widely. Egg mass surveys are then conducted in the fall at sites with high trap catches to further pinpoint population locations. Staff use these trapping and egg mass survey data to plan the next year's treatments, prioritizing sites that pose the highest risk of contributing to spongy moth spread.​

Aerial Applicator

DATCP and their contractors utilize geographic information system (GIS) technology to pinpoint and monitor where applications occur. DATCP uses GIS to plot treatment boundaries, and the planes are outfitted with GPS equipment to accurately apply product within those boundaries. Operations are monitored on computer screens in real time with a display that tracks the location of the plane and where product is being applied.

Aerial applicators contracted by DATCP and the Slow the Spread program are licensed by the state of Wisconsin and must meet all legal requirements of Wisconsin and the U.S. Environmental Protection Agency. ​

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