Gypsy Moth

Lymantria dispar, adult male

Lymantria dispar, adult male. Photo courtesy of http://www.entomart.be/

Gypsy moths are one of America’s most damaging pests, capable of defoliating and eventually destroying oaks and other trees. Accidentally introduced to the Boston area around 1870, they have now made their way to McHenry County. The county and municipalities are doing some spraying to combat the moth, but there are steps you can take on your own property.

Female laying egg mass

Female laying egg mass. Photo from US Forest Service http://www.fs.fed.us/

Destroy the egg masses: Between late August and early May, you can find the felt-textured, yellow-tan egg masses, which are about 1 1/2″ long, on tree trunks, picnic tables, the side of your house, etc. Soak them by spraying with an soy-based horticultural oil, or scrape them off with a putty knife and nuke them in the microwave on high for two minutes (eww!), or soak them for at least two days in soapy water. Stomping on them doesn’t work well – the eggs will survive to hatch into those voracious caterpillars.

caterpillar

photo from US Forest Service http://www.fs.fed.us/

Pick off the caterpillars: Sticky bands affixed around tree trunks will trap young caterpillars, or spraying BT (Bacillus thuringiensis) will kill them. As the caterpillars get bigger, these will no longer work. Try using a collection skirt, giving the caterpillars a place to “hide”. Cut a band of burlap about 18″ wide and a little longer than the distance around the tree. Wrap around the tree and tie around the middle. Fold the top half of the band down over the bottom half to form a loose skirt. Check every day or two by lifting the skirt, and scraping the caterpillars into soapy water.
Fool the adults: Pheromone flakes can be used to confuse the adults into not mating. No mating, no new eggs!

There is tons of information online – just Google “gypsy moth”. Talk to the county or your local authorities if you have concerns in your area.

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