Browntail Moth Update #8: June 26, 2025
We have confirmed pupation at all our monitoring sites that still had observable caterpillars. Avoid contact these pupal packets as they are impregnated with the irritating hairs from the last shed of the caterpillars which helps protect them from vertebrate predators at this vulnerable stage in their life cycle. Multiple individuals pupating in the same location can create a mass of packets which may serve to protect them further in a safety in numbers strategy. Management of these packets is neither recommended nor effective.
Image: A loose pupal packet created by a browntail moth caterpillar to shelter as it pupates in preparation for becoming an adult moth in Raymond.
We expect to get our first reports of adult browntail moth emergence in the next week or so; they usually emerge by the end of the first week of July. Although adult browntail moths have hairs on their abdomens, these hairs are not the toxic hairs found in the caterpillar stage. There is always a chance that adult moths can pick up residual caterpillar hairs when emerging from their pupal packets, so it is best to avoid contact with adult browntail moths.
Adult browntail moths are typically active from late June to early August and are highly attracted to light. The males fly directly toward the lights, where females can also be found resting on nearby foliage in proximity to the lights. It is recommended to turn off any non-essential outdoor lights during late June through early August to avoid attracting moths. Research from Dr. Angela Mech’s lab at UMaine Orono has found that swapping outdoor light blub color from white-blue to yellow hue bulb colors may be less attractive to browntail moth. A good option is the yellow bug light bulbs that are sold at many hardware stores. Avoiding bulbs on the UV side (cool blue hues) of the visible light spectrum is key. These include mercury vapor, UV bulbs, metal halide, and some LED bulbs.
FAQ: Should I use a bug zapper to help reduce browntail moth adults around my home?
No; bug zappers or similar insect killing devices are not recommended for management of adult browntail moths. Browntail moths adults are attracted to lights, and therefore will be attracted to the UV bulbs commonly used in bug zappers. While a bug zapper or a similar device may kill some adult browntail moths, it's likely to attract even more browntail moths, other pests, or native insect species that wouldn't have been drawn to the area - without any guarantee of effectiveness.
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The moths attracted to the UV lights on your property that are not killed will mate and reproduce in nearby trees, creating the next generation of browntail caterpillars.
Find more information on browntail moth life cycle, management, human and animal health concerns, and more on our FAQ page:
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