Location: Richland, WA USA
September 10, 2011 9:35 pm
I was at a picnic and I saw this guy on my shoe. Do you know what it is?
This strikingly marked beetle is a Locust Borer, Megacyllene robiniae, and it is an excellent mimic of stinging wasps like Yellow Jackets. Now that autumn is approaching and the goldenrod is beginning to bloom, we expect to be receiving numerous identification requests since the adults feed on pollen, especially goldenrod pollen. The larvae bore in the wood of Black Locust trees. According to BugGuide: “Eggs are laid in locust trees in the fall. Newly emerged larvae spend several months in tree trunks, first hibernating through the winter under the bark, then tunneling into trees in spring, eventually making tunnels about 4″ long and .25″ inch wide. They pupate late July/early August. Adult beetles emerge late August to September.” BugGuide also confirms our suspicions that this is not a native insect in the Pacific Northwest with this information: “Considered a serious pest of Black Locust trees; previously weakened or damaged trees are often killed by an infestation of the larvae. Previously confined to the native range of Black Locust in the northeast, it has spread with the trees throughout the US. Unfortunately Black Locust is used for reclamation and similar projects where trees are likely to be stressed out and thus more vulnerable to insect damage.” The Locust Borer was our Bug of the Month in October 2007.