The Maine Forest Service has announced that February 2022 has been recognized as Browntail Moth Awareness Month in Maine to encourage people to take advantage of the dormant season of the insect and join together to reduce impacts from Browntail-moth.
Let’s take some time to learn about these annoying creepy-crawlies.
What is the Browntail-moth and how did it get here?
The Browntail-moth (Euproctis Chrysorrhoea) is a species of moth that was accidentally brought to Massachusetts from its native Europe in 1897. Browntail-moths are now found living in all New England states in addition to New Brunswick and Nova Scotia.
Why are Browntail-moths an issue?
There are 2 main issues when it comes to Browntail-moth: feeding and hairs.
The larval, or caterpillar, stage of the Browntail-moth feed on the greenery of hardwood trees and shrubs. Common host trees and shrubs include (but are not limited to): Oak, apple, crabapple, cherry, hawthorn, shadbush, service berry, and rugosa rose. These feeding habits can cause a decrease in plant growth, branch dieback, and in some cases death for the tree/shrub.
According to Allison Kanoti, the state entomologist for Maine, Browntail-moth-caterpillar hairs are barbed and hollow. And inside that hollow tube, there’s a reservoir of a toxin. The tiny (0.15mm) barbed hairs shed by the caterpillars can cause severe rashes, similar to poison ivy (which results from both a chemical reaction to the toxin in the hairs and a physical irritation as the barbed hairs become embedded in the skin.), headaches, eye irritation, and respiratory problems which can last anywhere from a few hours to several weeks.
These microscopic hairs settle on line-drying clothing, backyard picnic tables, patio furniture and the ground beneath infested trees. The hairs can easily be stirred up by wind, outdoor chores such as mowing, raking, gardening, sweeping, and outdoor activities such as hiking/walking, biking, fishing, etc., and the hairs remain toxic for 1-3 years!
What do they look like?
Browntail-moths are most likely to be seen and recognized in their caterpillar and moth stages.
Caterpillar stage: Browntail-moth caterpillars grow to about 1.5 inches in length. They are dark brown with broken white stripes running along either side of their bodies. They have two obvious red/orange dots on their back and are covered in small hairs.
Moth stage: Adult Browntail-moths have a wingspan that is about 1.5 inches. They have snow white wings/bodies, with tufts of brown hair on the tips of their abdomens.
Don’t be fooled by these innocent Browntail-moth look-alikes!:
While they may have some features in common with the Browntail-moth, these caterpillars do not pose the same threats as Browntail-moths do.
Browntail-moths produce one generation per year and have four life stages: egg, larval, pupal, and adult.
As the diagram above shows Browntail-moth caterpillars become active in the spring, leaving their overwintering webs to feed on newly emerged leaves of their host plant until they are fully grown, usually around the end of June, and then form their cocoons (these are often found between leaves on trees, under eaves, picnic tables, decks, etc.). Adult moths emerge in late July and August, and female moths begin their oviposition (the egg-laying process.) They can produce between 200-400 eggs, which they protect by covering them with brown hairs from their body. When the eggs hatch towards the end of August, colonies of caterpillars build winter webs on the tips of branches. These webs, made of white silk tightly woven around a leaf or small number of leaves, can be 2-5 inches long, and can house anywhere from 25 to 400 caterpillars.
How to limit your exposure to Browntail-moth
- Avoid places heavily infested with caterpillars
- Keep car and house windows closed. Airborne hairs can settle onto indoor surfaces in high-risk areas.
- When performing activities outdoors choose damp days or wet the areas you are working in. Moisture helps keep the hairs from becoming airborne.
- Wear long sleeves, pants, and a hat and tightly secure clothing around the neck, wrists, and ankles.
- In areas of high infestation consider wearing goggles and a respirator or cloth mask, especially if you are prone to respiratory issues.
- Dry laundry inside during June and July to avoid hairs embedding into clothing.
What to do if exposed to Browntail-moth caterpillar hairs
- Before going indoors, use duct tape or a sticky-type lint roller to remove any hairs that may be embedded in your skin.
- Immediately wash exposed clothing (alone) in hot water and dry in the dryer.
- Take a cool 10–15-minute shower. Exposed skin can be gently scrubbed with a rough cloth to help remove embedded hairs.
Management/Removing of webs
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 when there are no leaves on the trees as the webs are more visible. Keep in mind that only the section of the branches that hold webs need to be removed. Equipment that can be used includes a pair of hand snips, hand saw, and/or pole pruner (which you can borrow from our lovely library!), eye protection, clothing to cover skin and gloves. Collect nests and burn or soak in soapy water 3-5 days then throw them away.
Pesticides can be used to control caterpillars if done before the end of May. The Maine Forest Service recommends contracting with a licensed pesticide applicator to control Browntail-moth. Products must be labeled for the site of treatment. A list of contractors willing to do Browntail-moth work can be found here: www.maine.gov/dacf/mfs/forest_health/invasive_threats/browntail_moth_info.htm
Want more information? Check out these sources!
-Maine Department of Agriculture Conservation & Forestry brochure: https://www.maine.gov/dacf/mfs/forest_health/documents/browntail_moth_brochure.pdf
-University of Maine: Cooperative Extension: https://extension.umaine.edu/home-and-garden-ipm/fact-sheets/common-name-listing/brown-tail-moth/