It was disappointing to reach Black Mesa, the furthest west destination for my June collecting trip through northwestern Oklahoma, only to discover that the whole region was dry as a bone. I spent an hour or so sweeping yellow roadside composites and got a few Typocerus confluens—a reasonably uncommon longhorned beetle, and another hour’s worth of beating oaks and junipers in the area produced a grand total of three Chrysobothris ignicollis, a very common jewel beetle associated with junipers in the southern Great Plains. This in glaring contrast to the veritable smörgåsbord of jewel and longhorned beetles I had encountered earlier in the week at Beaver Dunes, Alabaster Caverns, and Gloss Mountain State Parks. I had planned to spend at least a full day in the Black Mesa area—maybe two if the collecting was good, but as it was I couldn’t justify spending even another minute in the area. Unable to resist the siren call of more productive areas back to the east, I decided to cut my losses and return to those areas to close out the week. It was still early afternoon, and if I left immediately I would arrive back at Beaver Dunes (from where I had left just the previous evening) with at least a few hours to pad my series and perhaps even find something new.

Oberea oculaticollis Say 1824 | Beaver Dunes State Park, Beaver Co., Oklahoma

One area I wanted to take another look at was the small lake near the campground. I had beaten a few willow-feeding Agrilus spp. from the black willow (Salix nigra) and Poecilonota cyanipes from the cottonwoods (Populus deltoides) surrounding the reservoir. I desired better series of what I had collected the previous day, so I retraced my steps and beat most of the same trees I had beaten before. While I did quite well with P. cyanipes on the cottonwoods, again only a few Agrilus were beaten from the willows. I had nearly completed the circuit around the lake when I walked up to a small willow sapling that I had not sampled the previous day, gave it a whack over my sheet, and onto the sheet fell a nice longhorned beetle that I didn’t immediately recognize. At first I thought it was a species of Mecas due to the dense covering of gray pubescense, but the long and narrow form seemed much more agreeable with the genus Oberea. At any rate, seeing that it was something new for me I placed it back on a willow branch and began taking photos of it.

The dark integument and dense, grayish pubescence distinguish this species.

It was late in the day, and the beetle was unusually calm and cooperative and allowed me to take a number of shots, from which I have selected a few to show here. Once I had my fill of photographs, I slipped it into a vial for safe-keeping while I disassembled and stowed my camera equipment, and after I was finished I pulled out the vial with one hand and reached for my bottle dropper of ethyl acetate with the other. I have a technique to unscrew both the vial and the bottle with the fingers of the hand that is holding them, lifting both caps simultaneously, dropping a few drops of ethyl acetate into the vial, and again simultaneously placing both caps back in place and screwing them shut. This minimizes the time the cap is off the vial while the insect is in it, thus minimizing the chance of the insect escaping during the process. In this case, however, as I was trying to do this a dog-pecker gnat flew right at my eye, and I instinctively swiped at it with my left hand—the one holding the vial with the beetle in it! Of course, the cap was off, and the beetle when sailing out of the vial and immediately took flight. All I could do is just stand there dumbfounded at my stupidity. I did go back and beat the same sapling (and every other willow tree) on my way back in a last ditch effort to recollect the species, but fortune was not with me at this time.

This adult on black willow (Salix nigra) is the first indication of its host plant.

Once I returned home and had a chance to examine the photos more carefully, I learned that I had photographed Oberea oculaticollis Say 1824, a longhorned beetle distributed in central North America from Manitoba to Texas and distinguished, not surprisingly, by its dark integument and dense, grayish pubescence (Chemsak & Linsley 1995). Not only have I never before encountered this species, but it is also completely lacking in my collection. As far as I can tell, no host information has been recorded for this species, so my collection of an adult on willow might be the first clue as to its host plant. Without a voucher specimen, however, I am reluctant to publish the record and will have to keep this spot in mind for possible future collection of the species.

REFERENCE:

Linsley, E. G. & J. A. Chemsak.  1995. The Cerambycidae of North America. Part VII, No. 2: Taxonomy and classification of the subfamily Lamiinae, tribes Acanthocinini through Hemilophini. University of California Publications in Entomology 114:1–292.

Copyright © Ted C. MacRae 2013