Time to whack winter moth

Tim Forsberg
Posted 4/23/15

By TIM FORSBERG

Before being buried by last winter’s snow, Warwick residents dealt with flurries of another kind: winter moths.

The invasive species Operophtera brumata, known better as the …

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Time to whack winter moth

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Before being buried by last winter’s snow, Warwick residents dealt with flurries of another kind: winter moths.

The invasive species Operophtera brumata, known better as the winter moth, was out in force last season after Thanksgiving and was seen throughout the city. Adult insects were spotted congregating by the hundreds or thousands on lights, houses, cars and home interiors and exteriors, becoming a nuisance for many.

And while winter was ferocious and the adults are long gone, the next generation is now here.

“They’ve just started hatching, and they’re quite healthy,” said Heather Faubert, a research assistant at the University of Rhode Island’s Department of Plant Sciences and Entomology, a specialist who has been closely monitoring the bug in Rhode Island. “They’re doing just what we’d expect healthy eggs to do.”

The moth arrived in Canada in tree wood brought by ship from Europe during the early 20th century. The insects made their way to Rhode Island around 2005 and were first noticed in Bristol and Warwick. Until the last few years, distribution in Rhode Island was not widespread. With no native predators, however, they can now be found throughout the state.

This creature has a particularly unusual life cycle, becoming an adult after the late fall frost. The females, which are flightless and remain largely unseen, laid eggs in the crevices of tree bark last year that have lain dormant. The eggs start out orange in color, and then they turn blue just before they hatch.

“I put up bands on the trees in the fall to stop the females as they were coming up from the ground, so they would stop and lay a lot of eggs,” said Faubert of monitoring stations throughout the state, including the Rocky Point Blueberry Farm. “I took down the bands about a month ago and we’ve been monitoring eggs at five different locations and they just started turning blue last week, and they just started hatching on Saturday.”

Hatching caterpillars will crawl up trees and drill into the leaf buds as they are starting to swell and open, or feast on already open leaves, which can kill the plant. The caterpillars will feed until mid June, grow to about an inch in size, and then migrate down the trees and into the soil to pupate until they emerge as adults.

While there wasn’t much that residents could do last year to control the population once the insect had reached adulthood, the tables have now turned.

“If someone is trying to protect their apples and blueberries, I would suggest they spray today. Blueberry and apple growers need to get them before they get into the buds because if they feed inside, they destroy it,” said Faubert. “If they have landscape trees, one can wait [to spray] until the buds open up, and the caterpillars will still be small and exposed.”

If the caterpillars get inside the buds and the buds remain closed, they’re protected from any pesticides. Faubert recommends property owners use a biological insecticide to specifically target the moth.

“If they’re spraying now, use a Spinosad Insecticide, and there’s one available for homeowners called Captain Jack’s Dead Bug Brew,” said Faubert. “Once buds open, use a Bt product, Bacillus thuringiensis, products like DiPel, that only kill caterpillars. With this, the insects have to be feeding on sprayed leaves in order to kill them.”

In addition, Faubert and her team are working on a project to release a bio-control – an introduced predator – to counter the spread of the moth. The moth’s natural predator, a fly called Cyzenis albican, was first released at Goddard Park in 2011 and has finally become established. Considered a long-term solution, it will take several years for the flies to grow in population size to effectively control the moth.

In the meantime, spraying during the next few weeks may help control the moth’s spread.

“It seems like people’s flowering cherry trees get especially hard hit, so if someone wanted to choose one tree or two trees in their yard that they’d like to spray, that would be it,” recommended Faubert. “They seem to be suffering a lot.” 

 

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