Armored Stink Beetle in Joshua Tree National Park: What That Headstanding Black Beetle Is
Photo: abbybenson, CC0, via iNaturalist; cropped, with lettering added by Brian Russ Guides.
If you've walked a desert trail in Joshua Tree and spotted a matte-black beetle ambling along on stilt-like legs, there's a good chance you met the armored stink beetle, Eleodes armata. It's one of the easiest insects in the park to watch, because it doesn't scurry away. It just keeps walking, and if you crowd it, it plants its head down and its back end up. That's the famous headstand.
The park's own insect page (NPS) lists tarantulas, scorpions, harvester ants and the yucca moth, but doesn't mention this beetle at all. So here's what it's like to meet one, and how to plan your day so you actually do. If you're building a trip, my Joshua Tree National Park guide has the one- to three-day itineraries that put you on the trails where this beetle shows up.
What it is, and why it's worth a look
The armored stink beetle is a darkling beetle that lives in the dry country of the western United States and Mexico (Wikipedia). It's native, and it isn't unique to Joshua Tree. I'm picking it anyway because it's common here, it's out in the open, and it has a defense routine you can watch from a respectful distance.
The group it belongs to, Eleodes, is also called desert stink beetles or pinacate beetles. Think of them as the desert's cleanup crew. They eat decaying organic matter, including just-fallen flowers (PBS SoCal).
How to recognize it
Look for a dull black, oval beetle about the size of a raspberry (PBS SoCal), with long, thin legs and a head that looks small next to its rounded back. It walks in a fairly straight line and doesn't hurry for cover.
A word of honesty: there are several look-alike Eleodes species in the Southwest, and even expert commenters on BugGuide argue about which is which, partly over whether the spurs sit on one pair of legs or all of them. The photos below come from research-grade iNaturalist observations, which means other observers agreed on the name. If you want to be sure of an ID, the leg spurs are the thing to photograph.
Observed at Cap Rock, California, on October 7, 2019.
Photo: Katie Kucera, CC BY 4.0, via iNaturalist.
Where and when to look for it in Joshua Tree
This is the part the park's pages skip. Of the 25 research-grade records iNaturalist shows inside the park's boundary, a good share are from October, and the rest are spread across much of the year, with sightings from February through November. Named spots in those records include Cap Rock and Indian Cove, both easy to fit into a first visit. Open sandy flats and gravelly washes are the kind of ground you'll see in the photos here.
Time of day matters more than month. Desert stink beetles hide under rocks, logs and in animal burrows during the heat of the day and are more active around dawn and dusk (San Francisco Botanical Garden). In the hot months, several dozen may share one rodent burrow at midday (PBS SoCal). So the plan is simple: walk early or late, watch the ground a few steps ahead of you, and don't expect much at noon in summer.
If you're reading this in early November, the days are mild and beetles are still turning up in records from November. A morning walk at Cap Rock or Indian Cove, before the sun has warmed the sand, is a sensible bet. Nothing is guaranteed, of course.
Observed in Joshua Tree National Park, Riverside, California, on September 27, 2023.
Photo: agujaceratops, CC BY 4.0, via iNaturalist.
The headstand, and what it's really about
When a predator closes in, the beetle lowers its head, raises its rear and stands on its front legs. It's a warning. If the threat keeps coming, two glands in the abdomen can shoot out quinones, irritating chemicals that smell sharp and foul and can reach several body lengths (PBS SoCal). The spray bothers the mouths and eyes of birds and toads and repels ants (Bug of the Week).
One predator has a workaround. The grasshopper mouse grabs the beetle, jams its rear end into the dirt so the spray goes into the soil, and eats it from the head down. It's a neat bit of desert one-upmanship.
Observed at a location the record lists as Keys Ranch, Desert Hot Springs, California, on November 9, 2024.
Photo: dbugs, CC0, via iNaturalist.
Watching it responsibly
The spray isn't dangerous to people, but it isn't pleasant. One BugGuide poster notes it can stain fingers and is otherwise harmless (BugGuide), and another writer said the quinones turned his skin brown (Bug of the Week). Because the chemicals irritate mucous membranes, keep your hands away from your eyes if you've touched one.
The better answer is not to touch it. Joshua Tree says approaching, handling or capturing any wild animal in the park is illegal and harmful, and that spotlighting, meaning using artificial light to view wildlife, is prohibited (NPS). So no collecting, no jars, no flashlight sweeps. Crouch, take a photo, and let it walk on. If it does the headstand, you've already crowded it; back up a couple of steps.
Observed in Riverside County, California, on March 27, 2019.
Photo: Isaac Krone, CC BY 4.0, via iNaturalist.
Fitting it into your trip
You don't need a special outing. Build the beetle into the early-morning or late-afternoon stretch of whatever day you're already spending on a trail, keep your eyes on the ground, and treat a sighting as a bonus. The Joshua Tree National Park guide lays out how to pace one, two or three days so your best light and cooler hours land on the places you care about. If you want a bigger animal to look for, my post on coyotes in Joshua Tree covers where and when to watch them, and the two-day Joshua Tree itinerary shows how a strenuous weekend can fit together.
Before you go: see Joshua Tree National Park alerts and current conditions, checked daily, for current closures and what they mean for your trip.
This is an independent guide. It is not affiliated with or endorsed by the National Park Service. Conditions change; check the park's current alerts before you go.
