From a distance this beetle can easily be mistaken for a wasp or bee, even at a closer look they are often mistaken for M. caryae or M. decora. The adult beetle grows between 0.5 and 0.8 inches and have a W-shaped 3rd stripe on their elytra. Both sexes antenna are dark brown while male's antenna are two-thirds its body length and the female's are one-half. Their legs are reddish-brown. M. robiniae is often misidentified as M. caryae because the two look almost identical. The principal differences between the two species are that M. robiniae ONLY attacks live Black Locust (Robinia pseudoacacia) trees and is active in the fall whereas M. caryae attacks dead Hickory trees and is active in the spring.
The range has grown over the years seeing as it follows the R. pseudoacacia's range. As more and more people use the Black locust as an ornamental tree the range of M. robiniae grows. They can be found almost anywhere unprotected Black locust grow, often more abundant with Solidago. The females are often found running up and down Black Locust trunks in search for wounds to lay their eggs in. Both sexes are most common from late day to dusk. Because of the adults primary food they tend to stay in uncultivated fields and meadows. (info courtesy of Wikipedia)
This specimen was found near Wildwing Lake at the Kensington Metropark in Oakland County, Michigan. It was found feeding on Goldenrod flowers.