Cinnamon-Winged Flat Dragon (Rove Beetle)

2019 August 11

Sam and Rosie found this fairly large rove beetle crawling up the side of our house on June 7, 2019. It was about half an inch long.

CWFD.dorsal

It was also extremely fast, and unhappy about being exposed. My camera flash spooked it pretty badly. It scurried along rapidly, frequently waving its abdomen tip in the air in a threatening fashion, and then trying very hard to hide in whatever it percieved as being a crevice or shelter of any kind.

CWFD.side

The coloration, black with reddish-brown wing covers and abdomen tip, is a bit unusual for rove beetles, and I think I have it narrowed down to being Platydracus cinnamopterus. These don’t seem to have an English common name, but I’m pretty sure that “cinnamopterus” is pseudo-latin for “cinnamon wing”, so I think “Cinnamon-winged rove beetle” is probably fine. Of course, I’d have to ask the person who named it to be absolutely sure, and since Johann Gravenhorst died in 1857, that is clearly not going to happen.

And while we are on the subject of names, the BugGuide page for the Platydracus genus says that the name translates approximately to “Flat Dragon”, which is cool. And appropriate, seeing as how rove beetles are predatory. Here’s the best closeup I was able to get of the mandibles, and while they aren’t quite open we can see that they are the long, scimitar-shaped implements that are common in predatory insects.

CWFD.head.detail.dorsal

I did get another picture of the head from the side, but unfortunately the antenna blocks our view of the mandibles. The antenna are interesting, they look a lot like one of those beaded chains that used to be used a lot as pull-cords for switched light sockets.

CWFD.head.side.ant.detail

So, anyway, rove beetles are useful predators to have in the garden to keep the small vermin under control, so we let it go in the rhubarb patch.

2 Responses
  1. August 12, 2019

    I should be getting ready for work, but I don’t feel like it, so I’ll ask this: Are the number of nodules on the antenna species-specific? That is, this dude has 10. Do all Karl Rove Beetles have them?

  2. August 12, 2019

    If they are like most other insects, then the number of segments on the antenna is pretty likely to be constant all the way up to the family level. I just checked a few random members of the rove beetle family (Staphylinidae), and they all seem to have a total of eleven antenna segments (one base segment, and ten “beads”).

    Earwigs appear to have 13 antenna segments, so this is probably a good way to tell earwigs from rove beetles (which otherwise look pretty similar sometimes)

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