Natural Controls for Winter Moth

Winter Moth

It’s about to begin. In a couple of weeks here in southern New England, (late November), we’ll start to notice clouds of dull gray brown moths fluttering about at night, attracted to the glow of porch and street lights. Mating season for the Winter Moth, Operophtera brumata, is about to begin as both male and female moths emerge from their pupae. They will procreate into December, or as long as mild enough temperatures prevail.

In our recent research for the best methods to combat this destructive pest (Winter Moth caterpillars devour new plant growth on many of our most highly desirable ornamental trees and shrubs), we came across great news! University of Massachusetts Entomologist Joe Elkinton and his team have solid evidence that a parasitic fly, Cyzenis albicans, is an impressive natural control for Winter Moth. At four test sites where the parasite has been released throughout southeastern MA (Seekonk, Hingham, Falmouth and Wellesley)  populations of winter moth have dramatically decreased. Here is a link to an   article.

Isn’t that fantastic to read? However, while we are waiting for this helpful parasitic fly to move into our neighborhoods, we must begin preventive measures. It is necessary to understand the Winter Moth lifescycle to plan and time your defense.  The first meaure is to apply sticky tree bands around treasured specimens, which trap the females as they adhere and climb up tree trunks, emitting their sex pheromone to attract the males. After the mating scene has occurred, female moths continue to climb to the top of  trees and shrubs and then lay their eggs in the bark and crevices near branches. Adult moths die at this stage.

Other types of botanical controls can be applied over the winter and early spring. In late winter, dormant oil spray can be applied to branches to suffocate the eggs. In early spring, Bacillus thuringiensis a.k.a. BT, a beneficial bacteria, can be used to effectively control the caterpillars as they emerge from their egg sacs and seek nourishment from the young unfurling foliage. Spinosad is another bio insecticide, and is available to homes owner under product labels Monterey Garden Insect Spray and  to licensed pesticide applicators as the product Conserve. Care should be taken to avoid applying Spinosad when bees are active.

Recommended Further Reading

8 thoughts on “Natural Controls for Winter Moth”

  1. Good Question! Locally we checked around, and only Rosleand Nursery in Acushnet carries them. There are many mail order sources. Here’s one: Planet Naturals Amazon lists it as well; I guess they distribute everything now. We’re going to see If we can find a wholesale source for large quantities.

  2. I read that you have to fill the cracks under the sticky bands, to prevent the ladies from just moving on up under the band. Also, the sticky bands aren’t proven to work, per the UMass Extension article. Any other info? G

  3. Gail, the sticky bands are not the only mode of attack, but one measure of defense. Property owners with heavy infestation will definitely need to pursue additional methods. Catching the females before they lay eggs is step 1, suffocating the eggs with dormant oil is step 2. Once the caterpillars hatch they begin their feeding frenzy. Timing the spraying of BT and/or Spinosad in the earliest stages of activity is a priority. As trees/plants get defoliated, they become weakened and it requires a lot of energy for them to renew with new foliage. Once the caterpillars have had their fill of tasty leaves they pupate and burrow into the earth, and will emerge in greater numbers next November.

  4. Thanks! I didn’t think I had any, but probably do, now that I remember how the crabapple looked (duh) G

  5. We’ve got winter moth on an island off the coast of Portland maine and I’m leaving the porch light on and vacuuming the moths up. It is December, and on warm days the porch light is attracting a cloud of both male and female winter moth. The state entomologist identified the moth for me. The lights attract both the males and the females onto my porch (and away from the trees). We’ll see if community vacuuming helps prevent a population explosion.

  6. If using sticky banding around tree trunks, bear in mind that birds, such as brown creepers and nut hatches, who like to climb up tree trunks in search of insects, will get the (very) sticky stuff stuck to the feet, beaks and feathers. They may also try to pick off insects stuck to the band, thereby introducing the sticky material into their digestive tracts. This year I’m planning to put some mesh around the band to prevent this.

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