Winter moths arrive in a flurry

Tim Forsberg
Posted 11/28/14

An invasive species of moth is making its presence known in Warwick this time of year, and they aren’t wallet moths from too much holiday shopping.

The Operophtera brumata, better known as the …

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Winter moths arrive in a flurry

Posted

An invasive species of moth is making its presence known in Warwick this time of year, and they aren’t wallet moths from too much holiday shopping.

The Operophtera brumata, better known as the winter moth, is out in force this season and has been spotted throughout the city. Seen on lights, houses, cars and home interiors, the moths have become a nuisance for many.

David Gregg, Ph.D., director of the Rhode Island Natural History Survey, and Heather Faubert, a research assistant at the University of Rhode Island’s Department of Plant Sciences and Entomology, say there is little that can be done at this time.

“Massachusetts has been hit much harder and earlier, as they are that much closer to Nova Scotia, and they’ve been dealing with the situation longer than Rhode Island,” said Gregg. “In Rhode Island, for now, the population is only going to go up and get higher and higher each year.”

The winter moth is part of the Geometridae family, the same family that contains inchworms. Originally from Europe, the species arrived in North America during the early 20th century by way of the Canadian Maritimes, particularly Nova Scotia. It’s believed the moth made the trip in tree wood by ship.

The insects arrived in Rhode Island in 2004 and 2005 and were first noticed in Bristol and Warwick. Until the last few years, distribution of the insects in Rhode Island was patchy. With no native predators, they can now be found throughout the state.

This moth has an unusual life cycle, becoming an adult after the first frost in the late fall and early winter. Anytime there is a warm night after a hard frost more moths emerge. The females are flightless, remain largely unseen, and come out of the ground where they’ve developed throughout the summer. They then climb trees and put out pheromones to attract the males. The male moths are the ones that fly and can be seen by the hundreds on houses near outdoor lights.

“You shouldn’t leave your porch lights on at night; they disrupt moth’s breeding patterns and attract them,” said Gregg.

Females will soon lay eggs in the crevices of tree bark, which will lay dormant until spring. When the eggs hatch, caterpillars crawl up the tree and drill into the leaf buds as they are starting to swell and open. This is especially devastating, and possibly fatal, to plants. Hole-ridden leaves were spotted throughout Warwick this year.

“Similar to cutting out a paper snowflake, caterpillars will eat the developing leaves from the inside. They will do the same to flower buds, especially with blueberries and apples, which will prevent the future growth of fruit,” said Gregg.

“We’ve set up tree bands around the trees at the Rocky Point Blueberry Farm,” said Faubert. “These help congregate the moth’s eggs, and we monitor their progression.”

These invaders are difficult, if not impossible, to stop. There is an effort to release a bio-control – an introduced predator – to counter the spread of the moth.

“There is a fly that parasitizes winter moths. We’re working with researcher Joe Elkington from the University of Massachusetts on this,” said Faubert. “In the springtime, a trip is made to British Columbia to collect winter moths there that are parasitized. These specimens are then used to introduce the fly here.”

Called Cyzenis albican, the fly was released in five different locations across Rhode Island. The first was Goddard Park in 2011. This past year, researchers recovered the fly in Goddard, meaning the insect has become established.

“This is really good news for moth control,” said Faubert.

Both Faubert and Gregg added extensive research was conducted before the test began to prevent any unwanted side effects.

As if taken from a science fiction plot, this particular fly lays eggs on leaves that winter moth caterpillars accidentally eat. The eggs eventually hatch inside the caterpillar’s intestines, then eat their way outward and emerge as a fly while killing the moth.

“We’re never going to be rid of the moths,” said Faubert. “But what we need to do is have biological controls in place with enemies brought in so they can control the moths naturally.”

These controls remain a work in progress and are a long-term solution. Once these flies are established, it takes several years for the flies to grow in population size to effectively control the moth. In the meantime, patience is recommended for the rest of the season.

“At this point, when you see the adults flying around, it’s too late to control them. It’s not a good idea right now for people to be trying to spray them with chemicals or swatting them,” said Gregg. “One could swat all the flying males they want and it won’t make a dent. It’s much more important to try to save the plants you care about in the spring. Don’t stress yourself now.”

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  • starmote

    There are no native moths out now whose breeding patterns we have to worry about, so it seems leaving porch lights on would be a helpful thing to distract the males from breeding. I don't think the moths are active all night. A question- when the larvae are ready to change into adults, they drop to the ground to complete their maturing underground. How deep do they go for this? I wonder if disturbing the soil around our trees or shrubs would help disrupt them? If one is trying to protect a single tree or two, going out as soon as it gets dark and scrubbing the trunk with a really stiff brush will kill the adults there- until they have moved too high for us to reach them. You think I'm crazy for doing that, right? But I say, my bit of work vs. their bit of work is better than no work on my part at all.

    More info from the web: https://extension.umass.edu/landscape/fact-sheets/winter-moth-identification-management, and many other websites.

    Sunday, November 30, 2014 Report this

  • allent

    Good points starmote.

    Friday, December 12, 2014 Report this