The venerable locust borer, Megacyllene robiniae, was busily sticking its head into the knotweed flowers until I disturbed it. I took a few photos, then lifted my camera and realized the beetle was gone. Luckily, I was able to snap this photo of it folding out its wings to escape the paparazzi.
The locust borer is a longhorned beetle in the family Cerambycidae and develops as a larva inside of black locust (Robinia pseudoacacia), from which it emerges as an adult in the fall. It then nectars on flowers such as goldenrod and searches for a mate. This species takes its Batesian mimicry to the max--even the top of its abdomen, normally covered by its elytra--has the yellow markings that mimic a wasp. Now that's dedication.
I was hoping to find this species in my backyard, as I knew there are black locust trees around. I normally don't see adults of this beetle until the fall, so this was a nice surprise. Now to add this to my list of backyard species!