Maine Forest Service Surveys Show Adelgid Infestation; Control Beetles to be Released
November 25, 2008
Kennebunkport, MAINE -- As Mainers settle into their winter routines, hemlock woolly adelgids (HWA), invasive insects that destroy hemlocks, are gearing up for their winter feast in southern Maine, and Maine Forest Service staff are planning for a busy survey season.
Surveys conducted earlier this month by the Maine Forest Service show that the HWA has infested Kennebunkport and surrounding areas. Local residents are being asked to examine their trees for signs of the insect and report their findings to the forest service.
"The people of Maine are extremely important partners in looking for the hemlock woolly adelgid,” Allison Kanoti, MFS forest entomologist, said. “Even with full staffing we can only look at a small fraction of hemlocks at risk of adelgid infestation in the state.”
"State budget constraints have forced staff cuts,” the scientist said. “Now more than ever we need help from Maine citizens.”
Next week, MFS staff will release about 500 of a species of beetle that eats adelgids. It is hoped that the beetles will gain a foothold in the area and help limit the damage caused by HWA.
MFS staff is taking advantage of the increased visibility of the adelgid that results from fall and winter feeding. The overwintering generation of adelgid hatches from eggs in early summer, then finds a good place to feed. They settle onto the twig and spend the warm summer months in a kind of limbo that entomologists call “aestivation.” During this time they look like tiny, black sesame seeds on the new hemlock growth. In late October, the adelgids begin feeding and develop the fluffy white coat that provides protection from the elements and most predators and makes them easier to see.
This summer, a concerned Kennebunkport resident reported the presence of adelgid in the forest near his home after reading about HWA in a local paper. Because of the heavy summer rains this past year, most of the spring generation’s “wool” was washed away. As a result, MFS surveying for the insect in the Kennebunkport area was postponed until the winter generation resumed feeding.
Surveys to determine the extent of HWA’s presence in Kennebunkport, Kennebunk, Arundel, Biddeford and Saco were started in mid-November, after allowing new winter wool to build up. MFS entomology technician Wayne Searles found the tell-tale woolly masses on the first tree he walked up to in the first forest stand he surveyed
"The infestation is extensive but light in this area,” Searles reported. “I’ve found at least 50 infested trees and expect more will be found here.”
Searles and Kanoti believe that there are more infested forest areas in Kennebunkport and the surrounding towns. They are asking residents in southern and coastal Maine to examine hemlocks around their homes and in the forest for signs of this damaging insect.
"Adelgids will be found on the undersides of the outermost branchlets of hemlock, concentrated on the new growth,” Kanoti described. “They’re small this time of year, with most woolly masses measuring less than an eighth of an inch across.”
The adelgids are attached to the twigs with their mouthparts, so they won’t be crawling around. They are not located on the needles, but on the twigs themselves, and usually are visible only from the bottom.
"If you can see them from above, the populations are pretty high” Kanoti said.
In forest situations, the Maine Forest Service uses natural enemies of the adelgid to reduce this pest’s numbers. In Maine, two species of predator beetles that depend upon adelgid for survival have been released over the past four years. Sasajiscymnus tsugae, a tiny, black lady beetle, was first released in 2004 and is becoming established in two locations in Kittery and York.
Laricobius nigrinus, another tiny, black beetle, has been released more recently at several sites in Kittery, York and Saco. Although sampling has not yet turned up Laricobius, MFS entomologists are hopeful that it too will become established in southern Maine.
“We are at the northern edge of where this beetle can survive.” Kanoti said “Laricobius feeds during the winter months, so it is exposed during the extreme cold of winter. In southern and coastal Maine, winters are usually suitable for their survival. It’s those colder-than-average winters that may prevent Laricobius’ establishment.”
Next week, between Dec. 2-5, additional Laricobius beetles, hatched and raised in a Virginia Tech lab, will be liberated into the wilds of the York Water District, part of the Mount Agamenticus to the Sea Conservation Area.
These beetles will arrive hungry and will be introduced to the delicacy of Maine adelgid, Kanoti said. With time and a little luck, their descendants will help bring HWA populations down to a level that native hemlocks will be able to tolerate.
To report HWA, residents can call or email: Allison Kanoti, Maine Forest Service Insect and Disease Lab, 50 Hospital Street, Augusta, ME 04330; (207) 287-3147; allison.m.kanoti@maine.gov.
Help identifying hemlock and more information about the insect can be found on the forest service’s hemlock woolly adelgid web page: www.maineforestservice.org/HemlockWoollyAdelgid.htm.
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