False wireworms are the larvae of darkling beetles, which include the desert stink beetle, known scientifically as eleodes hispilabris. They are also referred to as pinacate beetles or clown beetles. Eleodes, derived from the Greek term for “olivelike” describes the general body shape and jet black coloration. Darkling is a common name applied to several genera and over 1,400 species within the family Tenebrionidae. Pinacate comes from the Aztec pinacatl, for “black beetle.” Stinkbug refers to the malodorous secretion emitted from the insect’s rear end. Clown beetle alludes to the habit of these beetles to do a “headstand” when threatened.
Upon being threatened, these beetles will race about and point their hindquarters at the object perceived as a threat and attempt to spray it with a foul-smelling secretion produced in the bug’s glands. Some can spray as far away as 18 inches. The spray does not wash off and can linger for hours.
When walking, pinacate beetles move with their front ends lowered and their rears raised. Their bodies are ovate to oblong, ranging in size between 0.4 and 1.4 inches long, and they are jet black or occasionally dark brown. They may be smooth or rough, and elongate or robust. The head is prominent and slightly narrowed behind the eyes. A few varieties have hair-like structures and what looks like a tail, which is actually elongated wings. Like all insects, they have six legs. Most species have antennae with eleven segments. Adults have five tarsal segments on the first two pairs of legs and only four tarsal segments on the third pair. The thickened, leathery wing covers may be ridged, smooth or granulate and protect the delicate flight wings, which in any case are fused together so the adults can’t fly.
They occur across ecosystems from open dunes to shrubs to mountains. The greatest diversity of the largest and smelliest occur in the deserts. The greatest overall diversity occurs in scrub and mountain regions. The beetles are often found under logs or in other detritus.
Most animals avoid contact with Eleodes due to the insect’s ability to produce its malodorous secretion. Grasshopper mice, however, get around this problem by grabbing the beetle, jamming its behind into the sand, and eating it head first. Other predators include burrowing owls, loggerhead shrikes and skunks.
Active year round, pinacate beetles are crepuscular and nocturnal (active at twilight, night and early sunrise) from spring to autumn. In fall, they revert to a more diurnal lifestyle. Pinacate beetles are one of the great walkers of the desert beetle world and are often encountered, seemingly wandering aimlessly. Studies have shown that they are probably in search of food, which they find by odor. Primarily, they consume detritus of grasses and forbs.
The larvae of certain Eleodes species are known as false wireworms, and they are a pest of some commercial crops in the Midwest, such as the seeds and seedlings of wheat, sorghum, all oilseeds including canola and linola, grain legumes and cereals, particularly in light, draining soils with a high organic content.
False wireworms overwinter as partially grown larvae or adults. Adults become active in the spring and lay their eggs in the soil. Larvae from these eggs hatch and mature by the end of the summer. A second egg-laying period occurs late in the summer. These eggs hatch and the partially grown larvae from this second generation will overwinter along with the surviving adults. The larvae feed on seeds, roots and underground stems of their hosts. With wheat, they usually attack the seed before germination.
From Wikipedia, commons.wikimedia.org, Orkin.com, https://entomology.k-state.edu/ and desertusa.com