Besides nursery inspections, our division assists with phytosanitary inspections in partnership with the USDA’s APHIS Plant Protection and Quarantine staff. In my area, I assist mainly with log inspections and ensure the commodities are relatively pest free before leaving the country or, if not, that they will be treated beforehand.
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- Figure 1: Painted hickory borer (Megacyllene caryae) emerging from a hickory (Carya spp.) log.
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- Figure 2: Painted hickory borer (Megacyllene caryae) on a hickory (Carya spp.) log with finger for size reference. Note the distinct “w” marking on elytra.
Recently I found an interesting pest on a hickory (Carya spp.) log. I occasionally find round-headed borers infesting logs, which are fairly common pests that often mine in or between the bark and sapwood of logs. Round-headed borers are the larval form of longhorned beetles (a.k.a. cerambycids [or beetles in the Cerambycidae family]). I normally just find the larvae during inspections, not the future life cycle stages like pupae or adults. However, I recently was able to spot painted hickory borer (Megacyllene caryae) adults emerging from a hickory log I inspected.
Painted hickory borers are colorful distinct longhorn beetles in the Cerambycidae family that can be distinguished by their yellow bands on an otherwise black body, including a “w” shaped band on the elytra (or wing coverings). They are important decomposers which help break down fallen logs for hickory trees as well as other hardwood species. However, because they bore into logs and firewood, they are considered pests for those commodities and are a species we look for when we perform inspections.
Painted hickory borers can be confused with their very similar relative, the locust borer (Megacyllene robiniae), but there are some easy ways to distinguish these longhorned beetle species. First, host is important to note since locust borers only infest black locust (Robinia pseudoacacia) trees. Also, painted hickory borer adults are active in spring, while locust borers adults are active in late summer/fall.
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- Figure 3: Painted hickory borer (Megacyllene caryae) lateral view under 20x magnification. Note the dense hairs, which also are what give the beetle its distinct coloration.
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- Figure 4: Painted hickory borer (Megacyllene caryae) dorsolateral view under 20x magnification.
Painted hickory borers do not often warrant management as they generally feed only on dead and decaying wood and do not affect living trees. Larvae generally feed on the inner bark of dead logs initially but can bore into the sapwood and heartwood as they develop. The biggest impact this has is on the lumber production since scarring to the wood can occur. Very few management activities will be successful once the borers are inside the logs, except for fumigation activities from a state approved facility. The best method of control is preventative such as not leaving logs lying around for long periods of time before processing or treating susceptible logs with an insecticide like bifenthrin to create an insecticidal barrier and prevent infestation. Otherwise, painted hickory borers are harmless, colorful longhorned beetles to be admired as they emerge in spring.
This article appeared in the Indiana Department of Natural Resources-Department of Entomology’s Weekly Review. You can find past reports and subscribe to their newsletter at https://www.in.gov/dnr/entomology/entomology-weekly-review.
