Insect Showdown in Shenandoah National Park
The trees in Shenandoah National Park are under attack from a destructive invasive insect called the hemlock wooly adelgid. The HWA has killed 95 percent of the park’s eastern hemlock trees. HWA appear as a small white wooly mass smaller than the erasure at the end of a pencil. HWA attach themselves to the base of the needles connected to the twigs of the hemlock trees and begins chomping down immediately. The trees usually die within four years of one of these bugs latching onto it. The first sign is the needles drying out and losing color, followed by a complete lack of new growth.
After battling the insects for years with insecticides the park officials are now trying a new method of attack. The officials are releasing a predatory beetle from Japan named Laricobius osakensis. These beetles are smaller than a grain of rice and will settle near the needles of the hemlocs close to where the HWA latch on. The beetles are host-specific predators of the HWA, so as number of HWA decline so will the beetles, negating any chance of simply replacing one insect with another.
What do you think of this warfare happening in one of our nation’s most beloved national parks?