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DEM Says Invasive Winter Moths Are Now in Flight

PROVIDENCE - The Department of Environmental Management reports that winter moth adult males are now in flight searching for flightless females with which to mate. These non-native invasive pests were first discovered in Rhode Island in 2004. DEM has received reports of them being found throughout much of Rhode Island, and particularly in the coastal communities of Warwick, Cranston, South Kingstown, Charlestown and Westerly. They have also been reported in Cumberland and Lincoln in the northeastern part of the state.

According to Bruce Payton, Rhode Island state forester and deputy chief of DEM's Division of Forest Environment, DEM began receiving reports of the emergence of winter moths beginning in late November, and expects to receive additional reports through the end of December. "Homeowners describe sometimes seeing hundreds of moths congregating around porch lights. It is no coincidence that this past spring these same communities witnessed an astonishing number of caterpillars defoliating oak, maple, ash, basswood, elm, beech and fruit trees," Payton said. Leaves on affected trees are filled with small holes and have a shotgun blast appearance.

Winter moth caterpillars are pale green with white longitudinal stripes running down both sides of the body. Also referred to as "loopers" or "inchworms," they are often found in association with both fall and spring cankerworms which look similar and have similar feeding patterns.

Payton noted that heavily defoliated trees will put out a second flush of leaves, which depletes a tree's stored energy supplies. "This is very stressful for the tree," he said. Adequate water is critical to trees during the time of defoliation, so if drought conditions occur, supplemental watering of the re-foliating trees may be necessary for their survival. Fertilizer application is not recommended at the time of defoliation. If residents decide to fertilize, they should contact a licensed arborist. The ideal time for fertilization is late winter or very early spring, but no later than mid-April.

In a continuing effort to control the winter moth population DEM has collaborated with researchers Heather Faubert, head of the URI Plant Protection Clinic, and Joseph Elkinton, PhD of the University of Massachusetts Amherst, who began implementing a biological control program to hopefully control this invader. In several Rhode Island communities the researchers have released a parasitoid fly that feeds exclusively on winter moth in early May. This will be the third year that this parasite has been released in the state, and the hope is that it will become established and eventually act as a control agent for the winter moth population. A natural enemy of the winter moth, Cyzenis albicans has been effective in limiting populations of winter moths in Nova Scotia. However, it will take several years for populations of the parasite to catch up with the population and spread of winter moths.

Rhode Island residents are asked to contact Paul Ricard in DEM's Division of Forest Environment at 568-2013 ext. 17 to report sightings of the winter moths.

Related links

Department or agency: Department of Environmental Management

Online: http://www.dem.ri.gov/

Release date: 12-17-2013

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