New Mexico: Black Desert Beetles

2019 January 20

In the first week of December 2018[1], we took a family trip to visit a friend who moved to Las Cruces, New Mexico some years ago (Hi, Dale!) So, I would like to spend a few posts on the insects that we saw while there. We didn’t see a huge variety, but those we did see were quite different from what we are used to here in Michigan. Let’s start today on the various large black beetles that we saw, most of which were various types of Desert Stink Beetles.

This first one we found while looking for gypsum crystals, near Rincon, between Las Cruces and Hatch[2]. It was a big, slow-moving beetle, about an inch long and jet black.



It was easy to catch and handle, and judging from the small, herbivorous mouthparts it wasn’t really capable of any sort of painful biting.


Now, if there’s one thing I’ve learned, it is that no insect is completely lacking in defenses against being eaten. This one can’t hide, can’t run, maybe can’t fly, can’t fight, and while its armor is pretty good, it isn’t good enough to fend off something looking to eat it. So clearly, it has something else going for it. And we get a hint at what this is from its peculiar behavior when it felt threatened – it would essentially stand on its head, with its abdomen tip sticking up in the air.


This is extremely suggestive that it was preparing to spray us with something noxious. And, when we got back to Dale’s place where we could look it up, it turns out to be one of the several species of Desert Stink Beetles in the genus Eleodes. And that is in fact what they do. They apparently hold the stink as a last resort, since it didn’t spray me while I was messing with it, but I bet if I had crushed it I would have gotten a snootful.

Later that day, we found several others which were all similar, but appeared to be different species. They varied in the shape of their pronotum (the segment just behind the head), in the shape of their abdomens, and in whether their wing covers were smooth or striated, but they all acted pretty similarly.




While their stench defense is on average apparently pretty good (seeing as how these beetles are all over the place), Dale’s guidebook mentioned that there are at least some desert rodent species that have found a workaround. It seems they will grab the beetle, stick it into the ground abdomen first so that it can’t spray, and then eat down from the head end. And, in fact, when we went up to White Sands the next day, Sandy found an example of exactly that: the end of a beetle abdomen stuck into the ground, with the rest all eaten away. The dark end was the part stuck into the sand, and the white part had been sticking up where it could be bleached by the sun.


[1] And the reason we went then, is that airfares are dramatically cheaper halfway between Thanksgiving and Christmas than they are during either of those times.

[2] Hatch isn’t a very big town, but it does have Sparky’s Burgers. Which, for some reason, is adorned with statuary from other restaurants. It’s as if they are trophies of the foes they have vanquished, like a headhunter showing off his shrunken heads.




Anyway, all around the area there are places where groundwater seeps up from below and evaporates. When it does this, the calcium sulfate that had been dissolved in the water crystallizes as gypsum, resulting in various shapes of crystals growing up right out of the ground.

One Response
  1. Kathryn Boyles permalink
    May 16, 2021

    Hello! I’m an Intern at White Sands national park. I’m trying to contact you to see if you would allow me to use the half eaten beetle photos in my pop up ranger presentation to teach the public about our grasshopper mouse. I would give full credit to the taker of the photo. Please feel free to email me. Love your work!

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