The USDA (United State Department of Agriculture) Forest Service has released several species of parasitic wasps as a biologic control method against the emerald ash borer (Agrilus planipennis Fairmaire) in 24 states*. These Asian wasps have already been aiding the fight against the emerald ash borer in Europe and Britain. They are host specific to emerald ash borer and won’t impact other similar species.
“These sting-less moths naturally target the larval and egg stages of the ash borer, which has killed an estimated 38m ash trees in urban and residential areas. The estimated cost of treating, removing and replacing the lost trees is $25bn, according to a report written by USDA and US Forest Service entomologists.”
“The tiniest of the wasps looks like a pepper flake on a white surface. It lays eggs inside ash borer eggs, preventing them from hatching. Three other wasps, one the size of a gnat, lay eggs inside ash borer larvae, halting development into adult beetles.”
Releasing these wasps won’t save this generation of trees. It is a long-term management plan that should protect the next generation of ash trees.
Note: Natural predators of immature emerald ash borer include the downy (Picoides pubescen), hairy (Picoides villosus) and red-bellied (Melanerpes carolinus) woodpeckers, but they only have a 16% impact on the insect.
*States include Colorado, Iowa, Michigan, New Hampshire, New York and Wisconsin. Texas and Georgia are to make it 26.
This information and the quoted paragraphs were brought to my attention by Maryann Whitman.