Gypsy Moth Suppression Program

Jeremy Lowell - Program Coordinator
(TBD) - Assistant Program Coordinator

Bay County Building
515 Center Avenue, Suite 503
Bay City, Michigan 48708-5941
Voice: (989) 895-4195

Gypsy Moth - Information about this Non-Native Invasive Insect

Overview of the Gypsy Moth Suppression Program 

  The Bay County Gypsy Moth Suppression Program was established in 1989 to control outbreak levels of the invasive species Lymantria dispar (Gypsy Moth) that were beginning to cause damage to area trees. Heavy infestations of the Gypsy Moth cause area wide damage to trees, woodlots and adjacent property when the caterpillar life stage eats the leaves off of area trees (defoliation). Gypsy Moths prefer to feed on oak, poplar, birch, willow, apple, and even spruce and pine. These are the dominant trees types in our landscape and woodlots. Defoliation makes the trees susceptible to disease and even death. The Gypsy Moth program serves to protect trees in Bay County from defoliation and damage from Gypsy Moth caterpillars by controlling Gypsy Moth Populations before they reach outbreak levels. 

2021 Bay County Spring Aerial Treatment to Control Gypsy Moth


The Bay County Gypsy Moth Suppression Program monitors for and works to suppress Gypsy Moths and other non-native pests that affect trees and plants in Bay County. In an effort to protect trees from feeding Gypsy Moth caterpillars and treatment was scheduled for Bay County in locations where Gypsy Moth populations have reached outbreak levels. Treatment took place on May 18, 2021 between the hours of 7:00 a.m. and 12:00 p.m.  On the day of treatment, weather parameters for spraying needed to be 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.  Weather conditions were within these parameters.  

Northern Bay County residents may have noticed a low-flying, yellow fixed-wing aircraft over wooded areas between 7:00 a.m. to 12:00 p.m. on the day of the treatment operations. The 13 wooded spray block area made up of 1,881 acres was treated and included areas located in the townships of Gibson, Mount Forest, Garfield, Kawkawlin, and Beaver. 


The aircraft was spraying Foray 48B, a naturally-occurring forest health product that contains the soil bacterium Bacillus thuringiensis kurstaki (Btk) that specifically affects Gypsy Moths caterpillars that are feeding at the time of treatment. BT has no known impact to non-target organisms such as humans, pets, birds, fish, and other insects. Field monitoring is performed afterwards to ensure that there are no adverse impacts. The product is an OMRI Certified organic, water-based, liquid formulation of BT that is applied to the forest canopy at a rate of ½ gallon per acre. The active ingredient is Bacillus thuringiensis variety Kurstaki (Btk). Btk will only affect the Gypsy Moth Caterpillars that will be feeding in the tree canopies at the time of application.

The Gypsy Moth Suppression Program has implemented a Pandemic Preparedness Plan which includes protective equipment, extra sanitation procedures and social distancing expectations in order to protect the health and safety of staff and the public during this treatment activity.  For more information contact Program Coordinator Jeremy Lowell at (989-895-4195). The Bay County Gypsy Moth Suppression Program is a division of the Bay County Environmental Affairs and Community Development Department.

The following are the insecticide and method of application:

  • Biological Insecticide Common Name: Foray 48B, this product is OMRI certified organic so it can be used on organic foods. Active Ingredient in the insecticide: Bacillus thuringiensis kurstaki (Btk)
  • Method of Application: Aerial application by a yellow fixed-wing airplane flying low over forested areas.

Areas to be treated:

Woodlots in Beaver, Garfield, Gibson, Kawkawlin, and Mt. Forest Townships will be treated for Gypsy Moth. Property owners in treatment areas have been notified by direct mail of the intent to treat the trees on their property.  Below is the 2021 Gypsy Moth Spray Block Treatment Map:

Additional 2021 Gypsy Moth Spray Treatment Area Information:

  • Beaver Township:  Treatment occurring in woodlots throughout the township, Approx. 15 acres, 1 treatment block
  • Garfield Township: Treatment occurring in woodlots throughout the township, Approx. 390 acres, 3 treatment blocks.
  • Gibson Township: Treatment occurring in woodlots throughout the township, Approx. 850 acres, 3 treatment blocks.
  • Kawkawlin Township: Treatment occurring in woodlots throughout the township, including Tobico Marsh DNR Property, Approx. 60 acres, 2 treatment blocks. 
  • Mount Forest Township:  Treatment occurring in woodlots throughout the township, Approx. 570 acres, 6 treatment blocks

Pesticide Label and Information for Foray 48B:

For further information or if you have questions, please contact Jeremy Lowell, Bay County Gypsy Moth Suppression Program Coordinator, at 989-895-4195 or at

Press Release for 2021 Bay County Gypsy Moth Aerial Treatment (forthcoming)

Landowner Authorization Forms

The Gypsy Moth Suppression Program staff sent out letters to landowners that have wood lots and wooded areas with the best sites to successfully monitor the Gypsy Moth Populations in Bay County. To conduct routine yearly monitoring, staff needs the cooperation of landowners like you. Letters were sent out to landowners describing how and when Gypsy Moth monitoring is conducted, along with a Landowner Authorization for Gypsy Moth Monitoring Form to fill out and send back to our department. The Landowner Authorization for Gypsy Moth Monitoring Form allows staff to conduct monitoring on your property in order to monitor and treat the invasive non-native Gypsy Moth. Staff will provide homeowners with field report updates on what they find in your area. By providing your e-mail address staff can provide you with the field report updates electronically. If you have any questions regarding this program, other invasive species, or any tree health concerns please contact Jeremy Lowell, Gypsy Moth Program Coordinator at 989-895-4195 or at None of your contact information will be shared outside of our office.

The 2020 Gypsy Moth Egg Mass Fall/Winter Monitoring is Competed! 

The Gypsy Moth Suppression Program completed the fall and winter Gypsy Moth egg mass monitoring in January 2021. This monitoring helps determine what locations will require spring treatment in 2021. Gypsy Moth monitoring done throughout this past spring and summer have shown that there are a few areas in Bay County where gypsy moth populations are still on the rise.  Areas with more than 300 egg masses per acre we scheduled for treatment in spring of 2021 where allowed.


Services Offered by the Gypsy Moth Suppression Program

To help protect the health of trees in Bay County, the Gypsy Moth Suppression Program provides the following services: 

  • Surveillance Monitoring:  Conduct surveillance monitoring in wooded areas to evaluate the prevalence and density of Gypsy Moth at its various life stages to determine if they are reaching outbreak level that can damage area trees. All wooded and residential areas of Bay County are monitored. When monitoring shows populations are at significant outbreak levels, treatment is provided to reduce the population and control the infestation. This includes determining where out-break level populations occur, contracting with an aerial applicator, and evaluation of treatment results.
  • Public Education:  Staff also provides education to the public on what to look for and best tree care practices to maintain healthy trees that can withstand attach by Gypsy Moths and other invasive species that could damage our trees. Staff presents educational programs for schools, property owners, and local civic groups, which include information on the life cycle of the Gypsy Moth, how it fits into our local ecology, and best management practices to control Gypsy Moths.
  • Treatment to Suppress Gypsy Moth:  Staff conduct treatment to help with the suppression of Gypsy Moth.  All treatments are compliant with National Pollution Discharge Elimination System (NPDES) permit requirements and Michigan Department of Agriculture and Rural Development’s (MDARD) Regulations 636 and 637 for the use of pesticides. Continue to follow guidelines and management practices outlined by USDA Forest Service and MDARD.

Click on the link above for answers to some of the Frequently Asked Questions about Gypsy Moth

Gypsy Moth Caterpillar Hatch Video

Baby Gypsy Moth Caterpillars are freshly hatched and ready to start eating the leaves off local trees.