An unsystematic catalog of the Coleopteran fauna in the environment surrounding the lab, biased toward the most common and easy to photograph. Most of the beetles on this page are large, black, usually shiny, and in the family Tenebrionidae. Scrolling down farther, you will find some interesting members of other families.

As time allows, each species will get its own page with a more detailed description and references.

Eleodes Beetles:

“…stay away from Eleodes; you can’t tell where one species leaves off and another begins.” Professor Josef Knull, Quoted in Triplehorn and Thomas, 2015, Trans Am Ent Soc 137: 251.

The genus Eleodes comprises flightless beetles in the family Tenebrionidae. All have defensive glands in the posterior abdomen that produce noxious chemicals that can be deployed against threats. There are at least six species of Eleodes commonly found around the lab. Some are easy to identify, others not so much.

To help me keep things straight, I have included the subgenus of each species (in parentheses), diagnostic characters, and relevant references below. You are welcome to ignore them.

Eleodes (Melaneleodes) carbonaria is an excellent example of the difficulty involved in identifying some Eleodes species. Eleodes carbonaria is particularly complicated, because there are at least three local subspecies that vary in both size and appearance. The shape and size of E. c. carbonaria is similar to those of E. c. obsoleta, but their elytra have very different patterns. At first glance, E. c. carbonaria looks like a smallish version of E. longicollis or a bigger version of E. extricata. A closer look shows that it is too small to be E. longicollis and has rows of small punctures on the elytra. It is bigger than E. extricata, which has more roughened elytra, Except for its size, E.c. obsoleta could be mistaken for E. obscura.

Distinguishing features (Triplehorn et al., 2009):

Ovate and convex, but highly variable. Elytral sculpting: E. c. carbonaria is punctate-striate and shiny with intervals slightly convex. E. c. obsoleta opaque with punctures muricate. 12-28 mm.

Eleodes (Eleodes) caudifera is a large, less common species. It is easily distinguished by the “tail” formed by extensions of the elytra.

Distinguishing features (Triplehorn et al., 2009):

Shape: Pronotum slightly convex, not strongly concave laterally, transversely rugose. Elytra slightly flattened and punctate-striate with intervals sparsely punctate and muricate laterally and apically. Both sexes have “tails,” with the male’s longer. 22-30 mm.

Eleodes (Litheleodes) extricata is the smallest local species. The elytra are slightly rugose, or roughened, compared to the larger E. carbonaria or E. longicollis.

Distinguishing features (Triplehorn et al., 2009):

Small, convex, fusiform, and glabrous. Pronotum has fine punctures. Elytra have approximate rows of coarse punctures. Profemora are dentate in males, sinuate in females. 11-15 mm.

Eleodes (Eleodes) hispilabrus is a medium-sized species with ridged elytra. Common and widespread in west. Similar to E. carbonaria obsoleta, but with narrower “waist” between prothorax and elytra, and spines on profemora of males (female sinuate). Smaller than E. obscura, and no “tails” like E. caudifera.

Distinguishing features (Triplehorn et al., 2009):

“….recognized from the members of the obscura group by the prominent dentiform apical angles of the prothorax [not 100%] and by the simple tarsi [i.e. the plantar groove is not interrupted by tufts of setae]; from all species of the subgenus Eleodes by the [usually] more or less deeply sulcate elytra, with convex intervals, and in never being caudate.” (Blaisdell, 1909). 18-29 mm.

Eleodes (Steneleodes) longicollis is possibly the most common species, found from spring through fall. Readily stands on its head when approached. Distinguished from other Eleodes by its relatively long, narrow appearance and smooth, shiny elytra.

Distinguishing features (Triplehorn et al., 2009):

Elongate to elongate-fusiform, subcylindrical, smooth and shiny. Pronotum broader than long, evenly convex. Elytra finely punctate and seriate. Females flatter and broader than males. 25-35 mm.

Eleodes (Eleodes) obscura is the largest species found in the area. Common throughout the spring and summer.

Size: 28-35 mm

Range: Broad distribution in western North America

Seasonailty: Spring through late summer.

More detailed information in the Eleodes obscura page.

Eleodes (Melaneleodes) tricostata is much less common and can be distinguished from other Eleodes species by the three prominent ridges running the lengths of the elytra. The prothorax is also flat, rough and lumpy.

Distinguishing features (Triplehorn et al., 2009):

Body more flattened and dull colored than other Eleodes species. Elytra widest anteriorly, and each elytrum has three costae (longitudinal ribs) in the middle, and one on the suture and the margin. Elytra covered in fine hairs. 13-23 mm.

Stenomorpha Beetles

There are several local species of Stenomorpha, most appearing in the fall. They are also Tenebrionids, but like all members of the subfamily Pimeliinae, do not have defensive glands. Some species are thought to be mimics of Eleodes beetles. The genus has received less attention than Eleodes, making definitive identification more challenging.

Stenomorpha opaca. Uncommon in late summer and fall.

Stenomorpha species that is relatively common in mid- to late summer. It looks like S. convexa, but there are no reports of that species in this region.

A common Stenomorpha, possibly S. marginata, that occurs in mid to late fall. It is just about the last species to be active in the year, and can be found until late October.

Philolithus

Although there is only one species of Philolithus, it deserves some prominence due to its abundance in the area and its reported mimicry of E. obscura. Like Stenomorpha, Philolithus is a member of the subfamily Pimeliinae.

Philolithus elatus emerges in late summer and can be found on roads, trails and anthills into the late fall. Until 2013, it was in its own genus, Gonasida.

More Tenebrionids

Embaphion contusum is another Tenebrionid beetle in the tribe Amphidorini. What this word salad means is that, like Eleodes species, Embaphion has stink glands. Note the elaborate “shoulders” on the thorax, and the ridge around the edges of the elytra. Uncommon in the neighborhood of the lab.

Eusattus beetles are nearly circular from above and dome-shaped in profile. Common in the summer.

Other Families

Longhorn Beetles: Cerambycidae

Cerambycidae is another large family of beetles, and it is expected that many will be found in the area over time.

Black cactus longhorn beetles (Moneilema armatum)live among cholla cactus. Their larvae burrow inside the cactus, feeding on roots and stems. Adults of some species are reported to mimic Eleodes longicollis.

Blister Beetles: Meloidae

Oil beetles in the genus Meloe are so named for the defensive secretions they release from their joints. They feed on foliage as adults, but are parasitic on native bees as larvae.

Burying and Carrion Beetles: Family Silphidae

As the name indicates, burying beetles prepare and bury vertebrate carcasses to provide a food source for their larvae.