I received an e-mail message from a concerned Ohio homeowner asking for an ID of several large beetles flying around their home. They were worried the beetles were emerging from something inside their home including recently purchased groceries and other supplies.
An attached image revealed the interlopers were Painted Hickory Borers (Megacyllene caryae). I replied asking about firewood and learned they had a sizable stack in their attached garage leftover from our mild winter.
The painted hickory borer is a type of longhorn beetle (family Cerambycidae), so-named because of their long antennae. However, not every longhorn beetle sports long antennae. Prior to the collapse of ash in Ohio from Emerald Ash Borer (EAB) (Agrilus planipennis, family Buprestidae), the Banded Ash Borer (Neoclytus caprea, Cerambycidae) was another beetle that commonly emerged from firewood in the spring. It has relatively short antennae for a longhorn beetle.
Painted hickory borers will only infest dead trees that died within one year or raw wood (e.g. firewood) that has been cut for less than one year. They target a wide range of hardwoods including their namesake host as well as ash, black locust, hackberry, honeylocust, oak, Osage orange, walnut, butternut, and occasionally maple.
The beetles present no risk to wood furniture, flooring, paneling, or other processed wood in homes, or wood used in home construction. They are just nuisance pests if they find their way into homes. However, their sudden appearance can be a surprise and cause concern; particularly inside log homes.
Painted hickory borers are sometimes mistaken for another native longhorn beetle that belongs to the same genus, the locust borer (M. robiniae). Both beetles are about the same size and share similar markings. However, locust borer adults emerge in late summer to early fall at about the same time common goldenrod (Solidago canadensis) is in full bloom. In fact, locust borer adults are commonly spotted on goldenrod partaking of the pollen and nectar.
More Boring Information
There is a wide range of native wood-boring insects; predominantly beetles, that infest the stems of stressed, dying and dead trees. Their lifestyle is revealed by entry and exit holes through the bark or when the bark falls off to expose tunnels or channels through various parts of the tree stem. Many of these beetles are known to emerge from firewood.
The native borers play an important role in forest ecology by initiating the biodegradation process to convert large wood fibers into smaller organic particles that ultimately support soil microorganisms important to soil health. Of course, when the borers infest fresh-cut logs used for lumber or firewood, they are considered forest products pests.
Be Alert to ALB
It's important not to lump all the evidence of wood-boring activity into "it's only natural." EAB taught us that lesson and Asian Longhorned Beetle (ALB) (Anoplophora glabripennis) continues to instruct.
Here are some key points relative to remaining alert for ALB:
1. Get an identification. Any large beetle emerging from firewood should be identified. It's well known that ALB will only infest living trees and firewood is obviously dead wood; however, the tree stems may have been infested when they were converted into firewood late last season.
2. Don't quibble about the time of the year. While it's too early in the season for ALB adults to emerge outdoors from their wood-tunneling abodes, all bets are off if the firewood is being held in a protected location, particularly indoors. The warm temperatures may speed-up development from larva to pupa to adult.
3. Don't just focus on maple firewood. ALB prefers maple; however, the beetle will infest trees belong to 12 genera, not just maple. Besides, it's not easy to identify maple once it's converted into firewood. That's why the Federal ALB quarantine restrictions simply state: "Firewood (all hardwood species) … "
4. It never hurts to call. The ODA/USDA APHIS ALB Cooperative Eradication Program in Ohio are the experts on all-things-ALB. If you spot a suspicious-looking beetle or suspicious evidence of wood-boring activity, you can call them at 513-381-7180. You can also get in touch with the national program at 1-866-702-9938.