Excerpts from Jim Conrad's
from the June 7, 2015 Newsletter issued from Río Lagartos, on the north-central coast of Yucatán, MÉXICO
INNUMERABLE ROVE BEETLES
On Monday the rainy season began with our first good rain in many weeks. The morning after the rain, I biked into the mangroves looking for frogs or whatever the rain might have released from a long heat- and drought-imposed estivation. The first rain creatures appeared en masse while I was still in town, in the form of clouds of tiny insects that tangled in my body hairs, got into my eyes and were inhaled if I breathed through my mouth or just breathed too hard through the nose. Below, you can see some caught in my knee hairs:
These are rove beetles, of the Rove Beetle Family, the Staphylinidae, which with about 58,000 species worldwide in thousands of genera is currently recognized as the largest family of beetles, and of course beetles constitute the largest group of insects, the order Coleoptera. Therefore it's good to be able to recognize a rove beetle. Normally that's easy, because the rove beetle's hard wing-covers, the elytra, are so short that they leave more than half of the insect's abdomen exposed. When rove beetles land they fold their flexible wings beneath their elytra, which the beetle at the right in the picture is in the process of doing.
With so many species and the species being little studied in the Yucatan, I suspected that it'd be hard to identify the ones encrusting my body that morning, and that turned out to be the case. That, these looking very unusual, with their heads bearing three hornlike projections pointed forward.
So, all we can say is that on the first morning after a rain here among the mangroves, clouds of one of 58,000 possible rove beetle species crowd the streets of Río Lagartos, Yucatán, causing señoras to frantically comb fingers through their hair trying to get them out, and causing bikers to pull up to the curb and cough awhile, trying to dislodge them from noses and lungs.
from the September 14, 2006 Newsletter issued from Polly's Bend, Garrard County, Kentucky, USA
ROVE BEETLES IN A COMPOST HEAP
I first mentioned Rove Beetles in my "Life in A Magnolia Blossom" essay of May 25, 2003. Down in the dewy zone beneath a magnolia blossom's bouquet of stamens where old stamens had fallen and now were turning brown and mushy, "Tiny, black, slender insects, maybe 1/8th of an inch long (3 mm), with strangely flexible abdomens segmented like cars on a kid's toy train skitter about... " Similar rove beetles populate my compost heap here, for that's another source of brown, mushy stuf.
About 3000 rove beetle species occur just in the US, and many are common. Happily, the group is fairly easy to identify because of a very curious, relatively obvious anatomical feature: Rove beetles' forewings are so short that they expose three to six abdominal segments. You can see this clearly at the above link.
The thing to keep in mind is that beetles (members of the insect order Coleoptera) bear two PAIRS of wings, thus four wings. Usually a beetle's forewings are hard like thick plastic, and often colorful. Think of a Japanese Beetle's rigid, shiny carapace, or a ladybug's. A beetle's hindwings are more like clear cellophane, like a fly's wings. In beetles, the hard forewings protect the delicate hindwings. When flying, the stiff forewings basically get in the way. Still, the hard-forewings-protecting-the-flimsy-hindwings strategy must be a good one overall, since Coleoptera is the world's largest insect order.
When you see how stubby rove beetle forewings are it's hard to imagine how the insects can fly. However, they are good fliers. The secret is that the cellophane- like hindwings fold up beneath the hard forewings.
Some of the longer, more slender rove beetles tend to curl up their rear-ends in a disconcertingly scorpion-like fashion. However, rove beetles don't sting. A few do have mandibles with which they can bite, but the ones I'm finding in magnolia blossoms and compost bins are perfectly harmless.
You might be interested in browsing Wikipedia's Rove Beetle Page with pictures of various species.