Browntail Moth Response
August 15, 2023 Update:
It appears that adult browntail moths have finished breeding and laying their eggs. Residents should be safe to turn on their outdoor lights without fear of attracting the adult moths.
This year’s adult moth population appeared to be greater than 2022, but still much less than 2021. At this point the egg sacs, pictured below, are likely to be hatching. The caterpillars are very tiny at this point and are not large enough to be shedding toxic hairs. The primary evidence you will see of their existence will be skeletonized leaves. They are not large enough to eat entire leaves so they eat the soft plant material between the veins of a leaf. If you notice these skeletonized leaves, you are likely to see winter nests this fall.
It is possible to treat trees with pesticide this fall, either injections or topical spraying. The best way to determine the most effective treatment, with the least ecological side-effects, for your specific application is to speak with a licensed pesticide applicator. You can find a list of pesticide applicators licensed by the State of Maine Pesticide Board here, List of Licensed Pesticide Applicators Willing to Treat Browntail Moth and/or Hemlock Woolly Adelgid: Browntail Moth (Euproctis chrysorrhoea): Forest Health & Monitoring: Bureau of Forestry: Maine DACF .
We encourage residents to still be vigilant about exposure to toxic BTM hairs. While the new generation of caterpillars are not yet shedding hairs, the cocoons of last year’s caterpillars are still fresh. These cocoons from July, pictured below, still contain the shed skin of the caterpillar, along with all those hairs. If you are pruning trees, these may break open. As the leaves fall from trees this autumn (it’s closer than you think), the old cocoons may break open during leaf raking activities. Once the cocoons are open, wind can stir up the hairs, causing them to come into contact with your skin, and cause an allergic reaction.
The latest information regarding the browntail moth infestation across the state can be found at the Knock Out Browntail webpage, maintained by the Maine Department of Agriculture, Conservation, and Forestry, www.maine.gov/dacf/knockoutbtm
Bangor Public Works will be holding a number of educational events this winter to teach people how to clip and dispose of BTM winter webs on their own properties. If you are interested in managing BTM on your own property, stay tuned to this page and our social media pages for dates!