11
$\begingroup$

These bugs are coming out of some wood that I cut and burned in Northern Indiana (USA) . I am not sure if it is coming out of a white ash, cherry or oak. We did have the emerald ash boarer come though the area -- is this an ash boarer?

Thanks.

Indiana firewood Bug

$\endgroup$
  • $\begingroup$ It's not an ash borer. You can learn more about Banded ash borers (Neoclytus caprea) that are sometimes confused for this borer species here. See here for information on the more commonly recognized emerald ash borer $\endgroup$ – theforestecologist Mar 2 '16 at 3:49
16
$\begingroup$

This is actually a Painted hickory borer (Megacyllene caryae).

According to the Virginia Cooperative Extension (and here), this species is frequently misidentified as a Locust Borer beetle (Megacyllene robiniae).

Here are their pictures side-by-side (M. robiniae on the left and M. caryae on the right):

Borer Beetles

Pretty similar, right? There are some differences though:

  • Appearance:

    • M. robiniae description (from Virginia Cooperative Extension):

      Both males and females have black bodies with bright yellow markings. These markings are most notable in the "W" on the first pair of wings. Legs are red and antennae are black. These long antennae place it among the "long-horned" beetles.

    • The distinction for M. caryae is the white 'W' stripe. From OSU Extension:

      The first marking from front-to-back on the elytra is also a yellow horizontal band; however, the second marking appears as a distinct "W" that is light yellow to cream-colored.

The following image from the Ohio State Extension better demonstrates the white W markings of M. caryae (similar to the OP's picture):

M. caryae

  • These two insects also differ in Behavior ( this is important).

    • From OSU Extension:

      Painted hickory borers emerge from cut wood in the spring and locust borers emerge from live trees in late summer to early fall.

    • Since the OP found this in the spring coming from firewood, it further points to the painted hickory borer.

  • Finally, they differ in the species they infest:

    • From the Virginia Cooperative Extension:

      The locust borer is a native insect that attacks black locust (Robinia pseudoacacia L.) and its ornamental cultivars... Unlike locust borer adults, painted hickory borer adults...attack stressed or recently cut hickory and other hardwoods.

    • M. caryae is named for it's preferred wood, the hickories (Carya spp.).

      • According to OSU Extension, M. caryae also commonly infests the recently dead wood of ash, black locust, hackberry, honeylocust, oak, Osage orange, walnut, and butternut trees.
    • M. robiniae, on the other hand, gets it name from the larvae living in and eating their typical host tree, black locust (Robinia pseudoacacia). Adults are also often found eating goldenrod species.

Should you be concerned? Not according to the OSU Extension page:

Fortunately, painted hickory borers only infest dead wood that has been cut for less than one year. ... The beetles will not infest older dead wood; they will not infest wood that has been dried or processed into home furnishings, or used as structural wood. So, beetles that emerge from infested firewood in or around a home are only a nuisance pest.

A quick search for M. caryae turns up few other sources, but you can find additional fact sheets for M. robiniae here, here, and here.


For those that don't know trees: here is a link to learn more about the common North America hickory species, and below are some images of common hickory species. More info about black locust (Robinia pseudoacacia) can be found here.

Carya Species

$\endgroup$
  • 4
    $\begingroup$ I updated this answer with the correct ID and the often misidentified look-alike (which I originally fell for). As a result, you get a two-for-one beetle lesson for the day :p $\endgroup$ – theforestecologist Mar 2 '16 at 3:43
  • 2
    $\begingroup$ Thank you for the well described and documented answer, as well as answering my follow up question: "Should I be concerned". $\endgroup$ – Tom Mar 2 '16 at 12:35
  • 1
    $\begingroup$ For fun: Mating Frenzy of painted hickory borers on youtube! $\endgroup$ – theforestecologist Feb 18 '17 at 19:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.