To combat them, researchers first brought in a beetle from the Pacific Northwest, known by the scientific name of Laricobius nigrinus.
“From an anecdotal standpoint, it’s been very encouraging,” Scott Salom, an entomologist in the College of Agriculture and Life Sciences at Virginia Tech, said of the beetle. “All the managers out there are excited about it.”
While effective, the latest anti-adelgid beetle has been more aggressive, with an appetite to match. Its scientific name is Laricobius osakensis.
The adelgid literally sucks the life out of hemlocks. Once hatched, they attack the tender shoot of a hemlock’s new growth, inserting a filament-like appendage into the base of the needle to feed on cells and wood tissue.
The infestation eventually turns a robust evergreen into what Rhea described as a gray ghost. The ravages of can be seen in the dull, shadowy profiles of hemlocks forests in the Southeast.
While the adelgid was discovered a little more than 60 years ago on the East Coast, it probably had taken up residence in hemlocks decades earlier. They likely hitched a ride on ornamental hemlocks shipped from Japan.
The introduction of this new, improved beetle to combat the bug illustrates the challenge of combatting an invasive species.
While chemical treatments can be used against the infestation, it is considered too labor intensive and expensive. It also raises environmental concerns.
So-called biological controls — using a nonnative predator to kill the invasive pest — also are a time-consuming endeavor.
The perfect match must be made, federal permission is required to bring in a nonnative bug, then it must be quarantined before it can be released to ensure it doesn’t introduce a new set of problems. They also must be bred to effective numbers to fight the pest and introduced to infested hemlock forests.