Gypsy Moth Treatment

Update
2021 Gypsy Moth aerial treatment was completed on Wednesday, May 19th, between 6:00 and 7:00 am. for six locations based on 2020 Fall Egg Mass Surveys. Areas are safe to use or to be in following treatment. Fall 2021 egg mass survey will be completed by the City to help in determining 2022 recommendations.

Gypsy Moth Treatment Update
The City of Rochester Hills performed 2020 Fall Egg Mass surveys/counts throughout the entire City. Based on that survey – six different locations were identified for aerial treatment to occur in May/June 2021 - See Map. Residents within these spray areas will receive a notification letter in the mail with more details. Treatment will be done with an organic product, commonly known as Bt, that is naturally found in soils and only affects young caterpillars. It is considered harmless to humans, pets, birds, bees, and other mammals. See FAQ for more information. The exact day and time of the spray will be determined by weather, including rain and wind conditions. Additional details regarding the treatment will be announced on this webpage. Outreach will be provided by the City to HOA’s and residents who reported Gypsy Moths in areas where higher Gypsy Moth populations were observed, but did not meet thresholds to be included in an aerial treatment.

All residents should report if they see significant gypsy moth activity near their property this summer and consider homeowner tactics to help protect your trees from Gypsy Moth. 


Gypsy Moths in Rochester Hills
Gypsy moths are monitored annually by the City’s Department of Parks and Natural Resources’ Forestry Unit. Based on phone calls received and gypsy moths observed out in the field, Arborists may be triggered to do a city-wide egg mass survey in the fall. Due to natural controls, gypsy moths within Rochester Hills have not been at concerning levels throughout the community since the city’s last spray in 2004. Over the past decade, gypsy moths throughout the city have been kept in check with little to no threats observed. However, in 2018, an increase in resident calls triggered a city-wide egg mass survey to be conducted to help determine the extent of gypsy moth populations and better identify areas that may be a threat to our community tree canopy. If you suspect you are seeing gypsy moth activity, larvae, or egg masses, please call us and help us target our future survey efforts. 

Click here to learn more about Gypsy Moths.

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