9/24/2021: The “everything’s bigger in Texas” Eleodes
I have always been a fan of Tenebrionid beetles (and surprisingly Silphids too), perhaps due to some formative experiences early in my bug keeping lifestyle wherein Alobates and similar good-size darklings would fall out from under ash bark during my forays for Michigan Parcoblatta sp. The American southwest is a hotbed for Tenebrionid species diversity and it’s always a challenge to resist the urge to collect every darkling one finds, knowing you may only find one of any species and that keeping everything separated, ID’d, and labeled on trips is usually a nightmare.
On the 2021 Arizona trip, we seemed to be a bit late in the year to find insane darkling beetle diversity as was present in August during previous trips, however I was able to collect sizable groups of some miscellaneous species. Among these were the largest darklings I have ever seen, out of the state where everything’s (supposedly) bigger: Texas.
TJ Ombrelle, hobby Tenebrionid expert extraordinaire, has proposed that they are Eleodes spinipes macrura, and the range and size fit the description. Another subspecies has been available in culture for a decade or so on and off, and this species has a reputation for being fairly difficult to continually propagate. I imagine that the sheer size of the macrura will only increase the difficulty of culturing this subspecies, as the limiting factor to many Eleodes in my experience has been figuring out pupation triggers and appropriate media/space for pupal cell construction. Regardless, I did have good success with the other spinipes subspecies in the distant past, having received a tiny group and successfully getting a pair to pupate. Unfortunately the adult female died from complications involving an elytra injury, but I have a lot more wisdom under my belt now and remain hopeful this other subspecies will go swimmingly.
As for the wild habits of this subspecies, they were out wandering aimlessly through ground-hugging plants at a rest stop in western Texas in the dead of the night. Some concurrent organisms were pocket mice, rainbow grasshoppers (more on these later!), and solifugids, although both the beetles and other animals were pretty widely spread out. The adults are most likely generalists as many Eleodes seem to be, with the larvae living in moist microhabitats like rodent burrows or near anthropogenic structures.
These may be the most exciting darkling beetle find from the trip (next to a lone Embaphion contusum adult, but I will reserve the hype for if/when larvae pop up), but if I can get some of the smaller Eleodes established I’ll do some write ups on them as well!
-Kyle