We’ve discovered two beetles in the last two weeks, one quite common and the other much rarer.
In Briones Regional Park we spotted a carrion beetle, Nicrophorus guttula (from Greek νεκρός + φορός, or “dead body carrier”) on the underside of a decomposing deer scapula. Nicrophorus beetles, which are quite common, often completely bury small carcasses, like dead mice or voles, and the two parents work together to strip the carrion of hair and prepare it for their offspring to eat. When the tiny larvae are born in the underground chamber, the mother beetle stridulates, like a cricket, to lead them to the food! These beetles, which do an invaluable service by stripping down dead animals, exhibit amazing parental cooperation and care, considering they are beetles.
Our Nicrophorus had a hitchhiker, too, a tiny phoracic mite, which rides on the beetle to get from carcass to carcass, and which may also help out the beetle by eating the eggs of flies that could hatch into larvae that compete for food with the beetle larvae.
The second beetle we found in Sunol Regional Wilderness on Friday. Though small, it was fierce, and threatened us with its impressive mandibles. We weren’t sure what it was at first, even after consulting our beetle field guide, but Prof. James Hogue of California State University, Northridge, kindly identified it for us as a tiger beetle in the genus Omus, probably Omus californicus. Tiger beetles live up to their name — they are fiercely predatory, which explains the chompers on this one!
Nicrophorus guttula on a deer scapula.
A hitchhiking or phoracic mite on the back of the Nicrophorus beetle. Note also the complex orange tip of the beetle’s antenna, which can smell the chemicals released by a decaying body from far away.
Tiger beetle, probably Omus californicus, with prominent mandibles. No vegetarian this!
Steven E. F. Brown 