| New Site | Old Home | Search | Communities | Counties | Southeast | Southwest | |
 |
| |
| ||||||||||||
Piñacate beetles
Last updated on Wednesday, January 01, 2003
Walking across town one afternoon, I saw a curious beetle trundling across the sidewalk: about an inch long and pure black, it walked with its hind end raised and its head down, as if its rear struts were jacked up high. I stopped and bent down to watch it. When it noticed me, it stood stiffly, and stretching its long hind legs to their fullest extent, thrusting its rear end upwards. That, plus the curious upended walk, gave its identity away: a Piñacate beetle.
Piñacate beetles are among the most conspicuous insects in the Southwest. Over a hundred species live from lowland deserts to foothills to piñon-juniper woodlands. Feeding on minute particles of wind-blown organic matter and fungus, Piñacate beetles help recycle nutrients and keep arid-country soils fertile.
Because there are so many kinds of these large, jet black beetles, they have acquired several common names. They are also called "stinkbugs" because they spray a noxious, foul-tasting black liquid that smells like kerosene from the tip of their abdomen to repel predators like ants, scorpions, and tarantulas. In Navajo, the name for these common beetles is the same as that used for another "beetle," the Volkswagen car!
Piñacate beetles are elegantly suited to arid country life: their ungainly, up-tilted posture raises them from the hot ground and allows them to collect nighttime dew, channeling droplets formed on their back into their mouth. An insulating air space under their fused wing covers helps buffer them from both heat and cold. (They also burrow into the soil or seek shade to keep from baking on hot summer days.)
Piñacate beetles' jet black color explains why the one that I saw was active in mid-winter, when most insects cannot survive the cold: being black allows Piñacate beetles to collect solar heat - in full sun, a black object absorbs 25 percent more heat than a white one. The black pigment also screens their tissues from ultraviolet radiation and strengthens their shell against abrasive desert soils.
Some predators have learned to disarm the stinky spray in order to dine on these large, succulent beetles: When a Piñacate beetle wanders into a black widow spider's web, the spider simply flings a line around it to tie it down, and stays out of range until the beetle exhausts its spray. Grasshopper mice grab the beetles and swiftly stuff their abdomen into the soil, then consume the juicy beetle at leisure.
The beetle I watched the other afternoon trundled smartly off the curb into another sort of danger: a busy street. Mindful of its noxious spray, I scooped it up with a piece of paper, placed it gently on the bare soil far from the street, and continued on my way.
|
||||||||||||