Beware of the Pine Engraver Beetle
The pine engraver beetle (PEB) unlike the mountain pine beetle (MPB) is not confined to the Black Hills in South Dakota but is a threat to the pine trees throughout western part of the state. It is a native bug that normally attacks dying, dead, recently transplanted, drought stressed or hail-damaged trees. Therefore, it can become a killer during periods of drought which weakens tree’s defenses.
Adult PEBs overwinter under the bark or in surrounding litter at the tree base. They are adults now and will be coming out in mid-April to May depending on location and weather conditions. They begin flying when daytime temperatures are in the 60’s. Initially the males enter trees, construct cavities under the bark and attract females by releasing pheromones. After mating the females excavate egg Y-shaped or H-shaped galleries and lay eggs. Larva hatch, feed, grow into quarter inch long grubs that change into adults by autumn.
Adult PEBs bore and tunnel into trees leaving a yellowish or reddish-brown dust in bark crevices or around the base of the tree. Most of the time, they usually do not kill whole trees, usually only parts of the trees discolor, fade and die. However, subsequent attacks over time may cause infested trees to succumb and die.
Other indications of PEB infestation include the presence of woodpeckers and their damage to the tree bark in efforts to eat them. Small round holes in the bark of infested trees indicate that they have completed development in that part of the tree, have exited and moved to another part of the same tree or to neighboring trees.
To control PEBs, treat recently transplanted or injured trees with carbaryl or permethrin in mid-April and again in mid-summer. There are many products currently on the market containing these active ingredients. A product containing carbaryl is Garden Tech Sevin. Products containing permethrin include Astro, Bonide Borer-Miner Killer, Gordon’s Bug-No-More and Hi-Yield Garden Pet & Livestock Insect Control. Insecticides are used as drenching preventive sprays on the trunks and larger branches. These insecticides need to be applied prior to adult beetle infestation. Since PEBs have several generations, two treatments first in early spring and second during mid-summer are needed.
Actions taken to promote vigorous tree growth can help prevent PEB attacks. Recommendations include the following: watering during drought periods, avoiding root injuries, mechanical damage, compaction and disease; removing pruned branches from the vicinity, and chipping infested trees and branches.