Browntail Moth (see photos below)

The Browntail Moth (Euproctis chrysorrhoea) was accidentally brought to Massachusetts from its native Europe in 1897, and soon after spread to the rest of New England and also moved into New Brunswick and Nova Scotia. The caterpillars have a huge host range of plants that they feed upon. However, they especially love oak, birch, apple, crabapple, pear, peaches, plums and cherry trees. In addition to other hardwoods, they’ll also devour rose bushes that they encounter in the landscape after being dislodged from their primary host trees due to wind or other disturbances. Since apples, cherries, peaches, pears, and plums are all members of the rose family (Rosaceae), it’s not terribly surprising that they will also readily feed on rose leaves as well.  UMaine researchers also recently discovered that at least the later-instar caterpillars can also survive on conifers.

A major problem with this insect stems from the fact that the caterpillars and cocoons are armed with defensive, microscopic barbed hairs which can travel through the air and–for many people exposed to them—cause skin rashes, headaches, and sometimes breathing difficulties. The reactions on the skin can mimic insect bites in appearance and sensation (often with extreme and long-lasting itchiness), causing many people to frequently mistake them as signs of mite, flea, or bed bug infestations, especially when they wake up in the morning to discover several brand new welts on any number of seemingly random locations on their body. Further complicating the situation is the fact that the toxin in the hairs can remain viable for upwards of three years as long as the hairs remain dry and out of the elements. Also, the caterpillars use their hairs in the construction of their cocoons, which are often formed in protective places around window and door frames, under the overhangs of rooftops, under eaves/gutters, inside garages that have been left open, etc. Thus, encounters with fresh or even long-since empty cocoons will typically result in additional exposures to the hairs.

The moths are attracted to light, fly at night, and are active in July and August.  They have a wingspread of about 1.5 inches (36-42 mm).  The wings and midsection are solid white on both the male and the female.  The abdomen has brown on it, and the brown coloration extends along most of the upper surface of the abdomen in the male [male example], whereas in the female, the top (upper/dorsal surface) of the abdomen is white, but the tuft of brown hairs at the very end is considerably thicker/wider compared to the male [female example].  Fortunately, the hairs on the adult moths are not toxic so those hairs do not cause a skin rash. 

Browntail Moth (Adult Stage) Potential Lookalikes:

    • Fall Webworm Moth (sometimes) — Populations found in Maine and other northern portions of its range have wings that are sometimes solid white instead of having brown spots and patches all over them (Spotted Form of Fall Webworm); adults appear in Maine earlier than Browntail Moth (end of May and early June as opposed to July, respectively) (BugGuide.net)
    • Virginian Tiger Moth — A similar white moth sometimes occurring at the same time in Maine as the browntail moth (but starts about a month earlier) but with two distinctive black dots near the base of each forewing, and only a small amount of brown, if any, on the underside of the abdomen) (BugGuide.net)

Photos and Additional Information: