Browntail Moth - Euproctis chrysorrhoea (L.)

• The caterpillars are active at two times of the year. In mid-April, they emerge from their winter webs and begin feeding and growing until they reach their maximum size in June.
• The second batch of caterpillars hatch from their eggs in August and are active until early October when they enter their winter webs to hibernate, emerging the following spring.

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• The Maine Forest Service recommends clipping webs between October and mid-April before caterpillars emerge from winter webs and begin feeding on new leaves.
• This task is more easily accomplished after the leaves have fallen from the trees as the webs are more visible.
• Web removal after mid-April when the caterpillars have emerged is not recommended as it is less effective and pruning wounds can be more damaging to trees and shrubs at this time of year.

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• When working in heavily infested areas, wear proper protective equipment to reduce exposure including:
  • Long sleeves
  • Long pants
  • Goggles
  • Dust mask/respirator
  • Hat
  • Disposable coveralls
• Avoid heavily infested areas between April and August, don't use leaf blowers or lawnmowers on dry days in these areas
• Using pre-contact poison ivy wipes can help minimize hairs sticking into exposed skin
• Do yardwork on wet days, which decreases the likelihood that the hairs will become airborne.
• Make sure to use a HEPA filter on a wet/dry vacuum to decrease the likelihood that the hairs will become airborne.
• Do not dry laundry outside in infested areas.

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• Some libraries have sets of pole pruners for loan. You may also be able to rent pole pruners.
• With care, a stable ladder, such as an orchard ladder or a lift can help in access to higher webs
• Some trees are too big to practically manage through web clipping, even by professional arborists. Properly applied insecticides can work for population reduction in these trees.
• The Maine Forest Service maintains a list of licensed arborists providing pruning services that can be found at www.maine.gov/dacf/mfs/forest_health/invasive_threats/browntail_moth_info.htm.

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• The greatest risk for exposure to the toxic hairs is between April and July.
• Caterpillars, shed skins, and cocoons all have toxic hairs.
• The toxin is stable in the environment for one to three years and hairs can become airborne at any time.
• It is important to take precautions year-round in heavily infested areas.

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• The optimal timing for control of the caterpillars is when they are small.
• Injections that leave larger dead caterpillars with the associated hairs in your yard, either due to timing of injection or rate of product movement to leaves, are not ideal. In most years, controlling caterpillars before late-May is recommended.
• Timing of injection may depend upon product used, tree species, mode of pollination, seasonal development, and injection system. The Department of Agriculture Conservation and Forestry recommends working with an experienced and reputable licensed pesticide applicator for management of this pest.
• In any case, the label directions and other pesticide regulations must be followed. In addition, understanding of details regarding rate of translocation of the product to areas where the caterpillars are feeding and duration of product in leaf tissues and other parts is needed for optimal management.
• If a homeowner is intending to conduct treatments on their own they should be sure to understand and follow the label and know that information beyond what is on the label may be needed to understand what product best fits their needs.
• The product manufacturer, University of Maine Cooperative Extension Pest Management Office and Maine Forest Service Forest Health and Monitoring Division can provide additional guidance.

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Browntail web removal: Webs in small trees and shrubs, safely within reach of the ground, and without hazards such as powerlines, can be removed between October and March. Browntail caterpillars emerge from their webs and begin feeding in mid-April, therefore webs removed after this time will not contain caterpillars and not be effective. Destroy webs once removed (burn, soak for an extended period in soapy water, or dispose of in trash). With permission, you can do this on properties you don’t own or manage. If there are hazards, or you need to leave the ground, this is work for a licensed arborist.

Use extreme caution if burning webs. Never burn unless the branches have been clipped off. This type of burning requires a burn permit. For more information, please visit www.maineburnpermit.com and check the daily forest fire danger report.

Browntail caterpillar treatment: Pesticide applications are most effective for browntail caterpillars when the pesticide product can take effect before late May. Treatments after that time are not recommended and are not part of an effective integrated approach to management (or IPM strategy). Since caterpillars are already wandering to new locations, targeted applications are not possible. Further, pesticide applications at this time of year are more likely to impact other living species in your trees, including pollinators and native insects, without effectively reducing the impacts from browntail. At this time, there are many shed caterpillar skins and toxic hairs that have already built up in the environment. To have more effective control of browntail, plan to target the next generation of caterpillars by scouting out new winter webs this winter to determine which trees you may want to treat next spring

Applications must be consistent with the label directions. Consider hiring a licensed pesticide applicator. In most years, treatment should be effective (caterpillars killed) before late May. Later treatments do little to reduce both hairs in the environment and damage to hosts.

If you are managing browntail moth using pesticides within 250 feet of the mean high tide mark adjacent to coastal waters and extending upriver or upstream to the first bridge, additional rules apply.

If you are unlicensed, do not use this approach on properties that are not yours or are open to the public.

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Hire professional help to treat webs out of reach or near hazards on the property you own or manage. Line up help during fall or winter.

Licensed Professional Arborists can remove BTM webs in larger trees and shrubs (October to March).

Unmanned Aerial Vehicle (UAV) Operators with an FAA Remote Pilot License may provide services using UAVs with attachments that physically remove webs.There is no requirement that these operators have knowledge of tree care. As in working with any professional, confirm your prospective contractor is adequately insured and qualified to provide the service.

• Licensed Pesticide Applicators willing to treat Browntail Moth, Hemlock Woolly adelgid and/or Other Pests
• Licensed Drone Operators (PDF)
• Arborists willing to PRUNE browntail webs in the winter (PDF)

For large trees, there are very limited insecticidal products (PDF) that are readily available to and applied by unlicensed individuals and that can legally be applied to target trees and life stages of browntail moth.** In trees where the caterpillars' hairs cause a nuisance and where it is not practical to remove the webs, Licensed Pesticide Applicators may be able to use insecticides during the growing season to manage BTM.

**Acecaps are not registered for use in Maine because the label does not meet federal standards for pesticide labeling. It is therefore not legal to use Acecaps. The Maine Board of Pesticides Control has provided support to the manufacturer to explain what needs to be changed to come into compliance and encouraged the manufacturer to work with EPA to bring their label up to standards. If we become aware of a change in status, we will update this message. You can check the current registration status by entering the product name in this database.**

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• 2022 Browntail Moth Aerial Detection Survey (PDF)
• 2021 Browntail Moth Damage Survey (with 2020-2021 Winter Web Survey data) (PDF)
• 2020 Browntail Moth Aerial Detection Survey (PDF)
• 2019 Browntail Moth Aerial Detection Survey (PDF)

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• 2023 Browntail Moth Winter Web Moth Survey (PDF)
• 2022 Browntail Moth Winter Web Moth Survey (PDF)
• 2021 Browntail Moth Winter Web Moth Survey (PDF)
• 2020 Browntail Moth Winter Web Moth Survey (PDF)
• Maine Browntail Moth Roadside Population Assessment: Winter 2018 (PDF)

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Click the images below for larger shareable graphics perfect for use on social media or Download All Graphics

Image	Description / Suggested Social Media Text
	Got questions about browntail moth? 211 is there to answer them.
	Know your enemy and your friends. #KnockOutBTM, not silkmoths. Image credits: DACF except promethea larva BOMONA user Zelenaks, promethea adult BOMANA user JRTindall
	Learn how you can #KnockOutBTM and reduce the itch at www.maine.gov/dacf/knockoutbtm. “browntail” in brown font
	Learn how you can  #KnockOutBTM and reduce the itch at www.maine.gov/dacf/knockoutbtm. “browntail” in white font
	Knock out browntail banner logo “browntail” in brown font
	Knock out browntail banner logo “browntail” in white font
	Knock out browntail stacked logo without URL “browntail” in brown font
	Facebook-ready image. Learn how to safely remove and destroy browntail moth winter webs from the Maine Department of Agriculture, Conservation and Forestry at www.maine.gov/dacf/knockoutbtm  #KnockOutBTM
	To avoid encounters with the fuzzy caterpillars, remove and destroy browntail moth webs by April. Learn how from the Maine Department of Agriculture, Conservation and Forestry at www.maine.gov/dacf/knockoutbtm  #KnockOutBTM

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