Aerial Treatment to Control Gypsy Moth Caterpillars to Occur Between: May 23 to May 27, 2022

The Bay County Gypsy Moth Suppression Program monitors for and works to suppress Gypsy Moths (now referred to as Spongy Moth) and other non-native pests that affect trees and plants in Bay County. In an effort to protect trees from feeding Gypsy (Spongy) Moth caterpillars, treatment has been scheduled for Bay County where Gypsy (Spongy) Moth populations have reached outbreak levels. Treatment will occur in one day, between the dates of May 23rd to May 27th, weather permitting. Weather parameters for spraying are: light winds (3-10 miles per hour), humidity above 50% and less than 40% chance of rain predicted for the next four to six hours. If weather conditions are outside these parameters, spraying will be postponed until the next day or until conditions improve.

Throughout northern Bay County, 19 wooded areas made up of 3,727 total acres will be treated by a yellow airplane flying low over the trees tops. Spray operations will begin around 6AM and will continue until completed. Townships where treatment will be occurring include: Gibson, Mount Forest, Garfield, Pinconning, Kawkawlin, and Beaver. A map showing the general locations of the areas to be treated is attached.

The biological insecticide Foray 48B will be used for this treatment. Foray, a water-based insecticide formulation, is certified organic (OMRI) so it has low impact on non-target organisms such as humans, pets, birds, fish, and other insects. The active ingredient is Bacillus thuringiensis variety Kurstaki (Btk). Btk will only affect the Gypsy (Spongy) Moth Caterpillars that will be feeding in the tree canopies at the time of application.

If you have any questions, please contact Jeremy Lowell, Bay County Gypsy Moth Suppression Program, 515 Center Ave. Suite 503, Bay City, Michigan 48708, via telephone at 989-895-4195 or email at