Tuesday, January 15, 2013

Out of the Firewood and into the Parlor

Redheaded ash borer. Photo: Mike Wilder, NCCES
These striking photos were submitted to the PDIC as an online image sample. Several of these insects had been found crawling around furniture in a Rocky Mount, North Carolina residence. Our soon-to-retire entomologist Dave Stephan identified them as the redheaded ash borer, Neoclytus acuminatus, one of the most commonly reported of our "firewood beetles." Although it is called the redheaded ash borer, it can infest many different species of hardwood trees. Dave also provided the following information about this interesting situation.

Redheaded ash borer. Photo: Mike Wilder, NCCES
There are several species of longhorned beetles which can emerge from firewood in homes. Most of the species encountered this way in North Carolina belong to the genera Euderces, Megacyllene, Neoclytus and Phymatodes. Typically, females of these species lay their eggs in the bark of recently cut, storm damaged, or dying trees. The hatching larvae tunnel into the wood and complete their development in one year, although some species may take 2-3 years. Longhorned beetles in general spend their grub-like larval phase burrowing in wood, eventually pupating there. There is a certain chilling requirement for the insect to break diapause (hibernation). In simple terms, if the wood stays out in the cold long enough, the insect's body is primed for spring. When the wood is brought into the house, the warmth tricks the beetles into thinking that the winter has passed, and the adults emerge. Dave suspects that the insect is as surprised as the homeowner to find that it has emerged into a strange habitat. He says that the chance is "less than zero" that they will cause damage to wood products in the home, since they must lay eggs on a "green" tree with intact bark. They do not sting, transmit disease, or carry off children, but could bite (just a pinch) if handled roughly. To avoid the problem in the first place, burn firewood within two to three weeks of bringing it inside.

Firewood can be a means of moving more serious pests, too. See Rob Trickel's Guest Blog from November 5, 2012 for more information.