Yellow-Tailed Rove Beetle

2016 September 14

On June 7, 2016, Sam found this between the brick pavers that make up our front porch. It was about half an inch long (roughly the same size as an earwig).


Its most distinctive feature was the yellow tail. At first I thought it might be a female firefly, because some fireflies have wingless females, and the tail tip was sometimes dark,


but other times the tail tip was bright yellow, almost looking like it was glowing.


We checked it out in the dark pantry, though, and it turned out that its tail wasn’t actually emitting light. It is just an iridescence effect, and this is not a firefly after all. It was hard getting any pictures at all from the side, because it was way too active to stay still for that, but we did get this blurry picture through the side of a jar we put it into. We can see that in addition to the yellow on its abdomen tip, it also had yellow on the underside of its thorax, kind of like a vest.


The general body shape suggested that it was a rove beetle, which are a family of beetles with greatly reduced wing covers and elongated bodies. Searching Bug Guide for “rove beetle yellow tail” turned up a likely suspect right away: it is a Gold-and-Brown Rove Beetle, Ontholestes cingulatus. Like a lot of other rove beetles, these eat dead and rotting things, mostly carrion and fungi. And also like a lot of other rove beetles, it didn’t smell so nice, due to its chemical defenses. Which is probably what the flashing yellow tail is trying to warn us about.

One Response
  1. Mark Sturtevant permalink
    October 7, 2016

    Hiking across horse pastures, I would see these things patrolling around the piles of horse dung. They are fast and alert, and I have the impression they are predators, but I am not sure.

Comments are closed.