The Garden Spotter

Browntail Moths: the Scourge of Summer


When Bill pulled into the driveway, he noticed right away: The leaves of our beautiful maple in the back yard were starting to look like green Swiss cheese, and several of the smaller branches were stripped bare.

“Caterpillars!” he gasped.

Honestly, I had been so busy tidying things for our oldest son’s high school graduation that I hadn’t even bothered to look up.  Closer to the ground there had been weeds to pull, plants to move, grass to mow, and bushes to prune. Who had time to notice the canopy above?

But on close examination, all the signs were there; we’d finally been hit by the scourge of the brown tail moth.  Euproctis_chrysorrhoea_noushka31_02 (1)

New Englanders are well acquainted with the brown-tail, Euproctis chrysorrhoea, a European species first introduced mistakenly in Massachusetts in the late 19th century . From there, it spread to most of the other New England states, and has experienced big fluctuations in populations over the years, sometimes reaching the point of infestation, sometimes nearly dying out completely. Southern midcoast Maine is currently experiencing an infestation.

According to the Maine Forest Service, the browntail remains a high risk this summer for 13 cities and towns in the southern midcoast Maine area, including Bath, Brunswick, Topsham,  Freeport and Yarmouth.  But it’s also been spotted in other towns farther up the coast as well as farther inland.

Browntail moths post a grave risk to trees, as the caterpillars can defoliate them, depriving them of food. With two or three years of unchecked infestation, trees can die. Their preferred hosts, according to forest service officials, are hardwoods such as oak and maple as well as some shrubs such rosa rugosa.

How to Protect Your Trees from Brown Tail Moths

To protect your trees from the devastation of the browntail moth, it’s helpful to understand its life cycle. Briefly, the browntail goes from egg to larva to pupa to adult. It remains in its most destructive stage, the larval stage, the longest period, from August through June of the following year.

In the fall, the young larvae, or caterpillars, form dense silky webs. In what is perhaps the easiest and safest way of eradicating the critter, these larva-filled webs can be cut and destroyed, either by burning or submerging in a bucket of soapy water. It’s also possible to hire a tree company or certified arborist to remove the webs, especially those that are high up in the trees. Maine Forest Service provides a list of licensed chemical applicators upon request.

Some tree companies do spray insecticides, but they must be specially licensed and they are restricted from spraying chemicals close to waterways. This is recommended in early spring, before the larvae emerge from the webs.

Other ideas for control of browntail moths include introduction of predators, such as certain types of flies, and pest strips around the lower trunks of the trees to trap the caterpillars as they travel in the spring and early summer. Again, any method should be cleared with your local municipal arborist, the Maine Forest Service, or the University of Maine Cooperative Extension Service.

How to Protect Yourself from Brown Tail Moths

Trees or shrubs aren’t the only effect of browntail moths, however.

During the caterpillar stage, browntails are covered with tiny hairs, tiny hairs that can cause a rash or other allergic reaction in humans. These tiny hairs are shed up to four times during the summer months, and they remain a toxic threat for up to several years.

Tips for protecting yourself from browntail moths include mowing the lawn when its wet to prevent the tiny hairs from becoming airborne; keeping your head covered when you are around the affected trees; and washing hands immediately after working in the yard. Never touch the webs directly, as they may contain thousands of tiny hairs that could possibly be inhaled.

Should you have an adverse reaction, you should contact your doctor or consult your local pharmacist. Several area pharmacies have developed creams they’ve made available over the counter. In the event the hairs cause a respiratory problem – some asthmatics have reported breathing trouble – a trip to the doctor or emergency room might even be needed.

Wikimedia Commons photos

Cowshed UK


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