Project targets tree-killing insect
WOODSTOCK, N.Y. » In a race against time, a statewide initiative is looking to a species that is abundant on the West Coast to naturally manage an invasive insect that is killing New York trees.
The New York State Hemlock Initiative is currently researching biocontrol management opportunities to control the hemlock woolly adelgid, or HWA, according to a press release. Part of that research involves introducing Leucopis spp. silver flies in New York’s forests to manage the invasive pest from Japan. The silver flies are a natural predator of the hemlock woolly adelgid.
“We’ve been releasing silver flies since 2015,” Charlotte Malmborg, natural resources technician with the New York State Hemlock Initiative, said last Tuesday. The biocontrol releases are part of the initiative’s research, she said.
On May 15, members of the initiative, along with partners from the Catskill Center for Conservation and Development and the state Department of Environmental Conservation, released silver flies on hemlock trees on Overlook Mountain at Magic Meadow in Woodstock. The health of the trees there is at risk from the hemlock woolly adelgid, according to the Catskill Center.
Malmborg said 120 silver flies were released during the event. She said the silver flies are put in fine mesh bags, with at least five male and five female in each. The bags are then placed over branches of hemlock trees that are infested with the hemlock woolly adelgid, Malmborg said. She said the bags keep the silver flies in place so they will lay their eggs on the infested branches.
“The larva that hatch from the flies will eat the HWA eggs, which will then hopefully reduce the number of HWA that hatch,” Malmborg said. She said the initiative is very optimistic and has seen pretty reliable results from the larva. The results are determined by checking the bags later to see how many silver fly larva and hemlock woolly adelgid eggs are present, Malmborg said.
The biggest downside is the amount of time it will take to im-
plement this biocontrol method, Malmborg said. Silver flies are abundant on the West Coast and the ultimate goal is to naturally create populations that will manage the hemlock woolly adelgid on the East Coast, she said.
“That’s many years down the road,” Malmborg said. She added, though, that there are still many places in New York state that have not been infested by the pest, so the initiative is trying to beat time and implement biocontrol before more trees are affected.
The hemlock woolly adelgid has killed countless millions of native Eastern hemlock trees
on the East Coast and has been present in New York since the 1980s, according to the initiative’s press release. The Eastern hemlock is a foundation species in northeastern forests and help provide clean, cold water resources and occupy the base of the forest food web, the release said.
The initiative is headed by Mark Whitmore, a forest entomologist at Cornell University.
Malmborg said there are management strategies landowners can use to help protect their hemlock trees, adding that it is also important for any infestations to be reported.
More information is available on the initiative’s website at https://blogs.cornell.edu/ nyshemlockinitiative/.