DEAR JESSICA: This season we have been inundated with gypsy moth caterpillars that are destroying our oak trees and their foliage. They are voraciously devouring the leaves, and of course, after eating so much, they excrete all over our picnic tables, chairs, shed, cars, driveway. It has become disgusting. All we do is clean up their messes. We try to capture as many caterpillars as possible, but it is a losing battle. With the remnants of their shedding and the discarded pupa, combining with the aforementioned, it is a most horrible situation. Now they are emerging as moths, with thousands of them flying around all over the property.
We realize that the moths’ egg laying will continue this destructive cycle for next season. We are desperate, so much so that we are contemplating cutting down all the trees in the section of the yard that is causing the most problems. However, for us, cutting a tree down is a most unfortunate and desperate act.
Do you have any suggestions or recommendations on how to handle this prevalent infestation?
— Carlo and Lucy Fusco,
DEAR CARLO AND LUCY: Long Island saw quite a few gypsy moth outbreaks last year, so it stands to reason that eggs from the 2015 generation perpetuated the cycle this year. In fact, parts of the Northeast are experiencing the worst outbreak since the 1980s, when millions of acres were defoliated by the caterpillar. The kicker is that the insect, native to Asia, Europe and North Africa, was deliberately brought to Massachusetts by a French scientist with a hare-brained, silk-spinning business idea. A few of the insects escaped his Massachusetts home and multiplied like rabbits. Or maybe rabbits multiply like gypsy moths.
Oaks, as you might have deduced, are a favored food source for gypsy moth larvae, along with poplars, willows, basswoods, some species of birch and adlers, apples, some pines, spruces, cedars, hemlocks and beech. The good news is that the destruction they are causing to your oak isn’t likely to be fatal to the tree — but I know that’s not your main concern.
There is a gypsy moth-killing fungus that has been naturally keeping the population under control, for the most part, but it thrives in wet weather, as all fungi do, and the unusually dry weather this past spring worked against us.
To achieve control, hunt for egg masses in early fall and scrape them from branches, lawns, patio furniture and other surfaces in your yard. Each mass contains up to 1,000 eggs, so dropping them into a bucket of hot, soapy water to kill them will go a long way toward reducing the next generation’s population. Be sure to wear gloves, and never handle gypsy moth caterpillars, as their hairs can be very irritating to the skin, and some people are allergic to them.
Barrier bands wrapped around the base of trunks in early April will prevent caterpillars from climbing up trees to reach their food source. This is good because a starved caterpillar is a dead caterpillar. Look for a sticky product such as Tree Tanglefoot or Roxo Bug Glue, and ensure the barrier is tightly secured to the trunk without gaps around bumpy areas of bark. Keep an eye on installed barriers to ensure yard debris and other insects don’t adhere to their surfaces. If that happens, replace the barrier; it must remain sticky to be effective.
It’s too late for spraying, as that should have been done during spring to coincide with the susceptible stage of the moths’ life cycle. And, although effective if timed precisely, pesticides can threaten beneficial caterpillars that would become butterflies, which are important pollinators -- so use them only as a measure of last resort in the event the above measures fail. If you find it absolutely necessary, hire a certified arborist to do the job.
Regardless of the level of success your efforts attain, one problem will remain: gypsy moths do not read surveys or respect property lines. Typically, infestation covers a communitywide area, and if your neighbors’ trees are infested, chances are high their moths will be paying yours a visit, too. So keep your fingers crossed for those April showers.