Controlling bark beetles
There are several species of bark beetles. Most are tiny, rarely exceeding 1/3″. Adult bark beetles are strong fliers and are attracted to damaged or stressed host trees as well as pheromones produced by other members of their species. Many, if not all, bark beetles transport spores of fungi that can further weaken a tree, clogging its vascular system and damaging it before the bark beetles do.
Pulling off a portion of infested bark may reveal a winding pattern of beetle galleries. Galleries chewed by larvae of all species are packed with sawdustlike frass. Typical symptoms of bark beetle activity in a coniferous forest include “fading foliage” that may be faded green, yellowish, red or eventually brown, accumulations of reddish brown frass and bark bits, hardened, yellowish pitch tubes on the trunk and BB-sized emergence holes.
One of the few products labeled for bark beetles is Tengard. Apply Tengard to the lower branches and trunks prior to adult emergence. Adult emergence varies according to pest species, host tree, environmental conditions and geographic location.
Thorough coverage of bark is required for control.