Maine to release 10,000 predator lady beetles in hemlock woolly adelgid-infested stands in state's southern region, entomologist says biological-control effort is not 'silver bullet' but is best available tool to control pest
May 21, 2014
– Biological-control effort targets invasive insect attacking hemlock trees
Over the coming weeks, The Maine Department of Agriculture, Conservation and Forestry’s entomology staff will release more than 10,000 tiny, predator lady beetles in several hemlock woolly adelgid-infested stands in the southern region of the state.
The first release of the year will take place on May 29 in Portland’s Baxter Woods in cooperation with the City of Portland. This release is part of an integrated management approach in the city park that also includes monitoring by local high school students, chemical management of adelgid on legacy hemlocks and public education.
The tiny, black lady beetles, known as Sasajiscymnus tsugae, will be released to fight the hemlock woolly adelgid (HWA), an invasive insect that attacks hemlock trees.
Governor Paul R. LePage stressed the importance of public involvement in efforts to contain, eradicate and prevent invasive species. “Public awareness of the threats posed by invasive species like the HWA is critical to minimizing their impact,” said Governor LePage. “Once they have taken hold, it is very difficult and expensive to contain and/or eliminate them. That is why early detection by the public and Department professionals is important.”
The biological-control effort won’t eradicate the infestation, but it should reduce the HWA populations according to Allison Kanoti, forest entomologist, under the Maine Department of Agriculture, Conservation and Forestry (DACF.
“It is not a silver bullet, but it’s the best management tool we have in the forest at this time,” Kanoti said. “This is a long-term solution; results will not be immediate.”
The beetles will come from labs in Pennsylvania and North Carolina. Their release is made possible by federal grants from the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service – Plant Protection & Quarantine program and the US Forest Service.
Hemlock woolly adelgid (HWA) is a small, aphid-like insect that is covered with white, waxy wool-like material. This wool-like covering makes the insect resemble miniature cotton balls. It is most visible from late-October through July, with woolly masses located on the undersides of the twigs at the bases of the needles.
The insect, which came from Japan in the 1950s, causes deterioration of infested trees, including loss of needles, crown thinning and tree death. Hemlocks are a significant Maine tree species. Their presence along water bodies helps protect the forest floor from erosion and buffers water temperatures, which can affect such species as brook trout. Hemlocks also are important in deer wintering areas, are a favored landscape tree and contribute to the state’s forest products sector.
The adelgid begins its egg-laying in March. During the spring and summer there are thousands of offspring, called crawlers, crawling around, sifting down through the tree canopy and drifting on the breezes in infested hemlock forests. These young can be transferred to new locations by people, birds and other animals. Hemlock woolly adelgid can also be moved year round on live trees.
HWA has been found in at least 19 states. It was first detected in forest trees in Maine in Kittery in 2003. It has most recently been found in forest stands as far up the coast as Owls Head in Knox County and inland to Sanford in York County. Infestations on planted trees have been found from Lubec to Bangor and South, with the most recent detections in Bar Harbor, Blue Hill, Ellsworth, Northeast Harbor, and Sedgwick in Hancock County.
Homeowners are among the most frequent reporters of new locations of hemlock woolly adelgid. Other locations are reported by arborists, foresters, land trust stewards, students, tourists and occasionally even entomologists. If you think you’ve found hemlock woolly adelgid, please report your find to the Maine Forest Service.
For more information on invasive threats to Maine’s forest and trees, go to: http://www.maine.gov/forestpests#hwa
For more information about the Maine Department of Agriculture, Conservation and Forestry, go to: http://www.maine.gov/dacf