Thursday, April 25, 2019

Borids Are Not Bor-ing

Well, that will teach me to never go anywhere without a vial or other appropriate vessel for containing a live insect. It is impossible to know when you will be presented with an unusual or rare species, so best to be prepared. A case in point occurred on Saturday, April 20, while I was manning the booth for the Mile High Bug Club at the Earth Day expo in Garden of the Gods Park here in Colorado Springs.

Lecontia discicollis, 12-23 millimeters

We had erected a canopy over our table, and at one point I noticed the shadow of a beetle atop the white tarpaulin. I did not think much of it initially, but curiosity got the better of me and I went to inspect it. I am not a tall person, so all I could manage, even on my tip-toes, was a vague, rear perspective of the insect. It was enough to convince me this was something interesting, so I grabbed the beetle. It was shiny black, and slippery thanks to its convex, bullet-like shape.

Mile High Bug Club booth

A closer examination left me stumped. It reminded me of a bark-gnawing beetle in the family Trogossitidae, but those are highly agile and usually at least slightly iridescent or metallic. This beetle was jet black and decidedly slow-moving. Meanwhile, the antennae were bead-like and reminiscent of a darkling beetle (family Tenebrionidae). Few tenebrionids are so narrow-bodied, though, and those exposed jaws suggested it was something else.

Bark-gnawing beetle, Temnoscheila sp., Colorado

I had not packed any kind of container with me, even though I knew our booth would be in the visitor center parking lot. It has been a long winter and cool, slow, spring, so I wasn't expecting to see any insects.

I racked my brain for potential solutions. Ah, a little ziplock baggie I have my business cards in! Oops, so old it has a gaping hole in it. Now what? I pawed through the compartment in my backpack and managed to find a case for eyeglasses, which thankfully shuts tight enough to hold an invertebrate. In goes the beetle.

EBCD: Emergency Beetle Containment Device

Back home, I take a closer look and start leafing through my beetle books. Still scratching my head I look at all things related, even remotely, to darkling beetles. Lo and behold, I turned to an illustration that looked pretty much identical to my specimen. Above the drawing I read "Boridae," and "Family common name: The conifer bark beetles." Never heard of them. That is how diverse beetles are. Entire families can escape your attention.

Anyone hearing "bark beetle" assumes the creature in question is some type of forest pest, but many kinds of beetles associated with the trunks of trees have been assigned some derivative of "bark beetle," and almost none of them are the least bit destructive. That appears to be the case here, too, but we have a collective void of knowledge about borids.

The base of the antenna is concealed by a ridge, a helpful identification character

Consulting several references, I could find little information. The family is obscure enough that several books did not even include them, or were of sufficient vintage that the family did not yet exist. Previously, borids had been part of the Salpingidae (narrow-waisted bark beetles). Most other information I could excavate amounted to "found under bark on conifers." It seems these beetles also like their trees baked. Ok, singed. Fine, they are basically drawn to charred timber, three to five years after a fire.

Once I had the specimen in the right family, identifying the genus and species was easy. There are only two genera, with one species each, found north of Mexico. The one in my hand was Lecontia discicollis.

I turned to Facebook, in particular the group "Friends of Coleoptera at the Natural History Museum [London]," for more help. The resulting discussion included this shared passage from Pollock (2010) in the Handbook of Zoology, Coleoptera vol. II (Leschen, Beutel & Lawrence, eds.):

"Relatively little is known, or at least published, on the habits and habitats of members of Boridae....Larvae of Lecontia discicollis are also associated with dead conifers, and seemingly are restricted to moist decayed areas in the root system of standing trees killed by fire or bark beetles (Young et al. 1996)."

Another colleague added "Lecontia discicollis is not rare if you know how to find them. Fairly common in the Black Hills [South Dakota] in and around fire killed 8-15 year old Ponderosa pine, 3-5 years after death. Larvae in soft and moist white-rotted wood near and below ground-level."

The consensus seems to be that these may be common beetles, but because they occupy such a narrow, extreme niche, you are not likely to see them very often. I will consider myself lucky, then.

Sources: Elliott, Lynette, et al. 2005. "Family Boridae - Conifer Bark Beetles," Bugguide.net
Evans, Arthur V. 2014. Beetles of Eastern North America. Princeton, New Jersey: Princeton University Press. 560 pp.
Pollock, Darren A. 2002. "Boridae" in Arnett, Ross H., Michael C. Thomas, Paul E. Skelley, and J. Howard Frank. American Beetles volume 2. Boca Raton: CRC Press. pp. 534-536.

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