GIANT ROOT BORERS
According to popular lore, the great British biologist J. B. S. Haldane was asked what could be learned of God by studying nature, to which he quipped, "He seems to have an inordinate fondness for beetles." The truth matches the tale's essence, but falls short of its satisfying details, and I see no reason to wreck a good story.
Beetles certainly are a successful group, with roughly the same number of species as all other insects combined. Most of them are tiny and dull, but many of them are beautiful and spectacular. The African Goliath beetles (Goliathus spp.) are often said to be the largest beetles, though the South American Titanus giganteus greatly exceeds them in length, and probably in weight, as well. Even so, they are immense and wonderful creatures, and far more beautifully marked than any of their competitors in the hugeness competition. Surprisingly for such cumbersome things, the ones I've seen in nature have been arboreal, and seem to rarely come to the ground. During the brief tropical dusk, though, they fly about the canopy from one nectar-rich flowering tree to the next. It's hard to describe the flight of a beetle with a seven-inch wingspan, because it's really so improbable. It's like being buzzed by a winged box turtle. Of course they make a real racket--you can't miss one when it flies helicopter-like overhead, evoking strains of Wagner's Ride of the Valkyries.
Across much of Latin America, the Hercules Beetle (Dynastes hercules) is the most common very large beetle. Smaller than a Goliath, the pair of antler-like horns on the thorax and head of the male roughly double his length to around seven inches. At La Selva biological station I once took a night hike with several young biologists. One of these was a rather obnoxious lad whose personal boat was all too often commandeered by his bellicose ego. On this evening, the presence of a beautiful and charming female biologist was incentive enough for such a mutiny, and we were all subjected to great bluster and boasting for most of the evening. Suddenly a large Hercules Beetle, attracted to our flashlights, came flying toward us from two o’clock. Passing us by, it continued into the jungle on our opposite flank. A moment later it was back, and on the third pass it landed directly on the groin of our swashbuckling biologist. When a beetle of this size lands, any sudden perceived attack will instantly provoke it to grasp its substrate with all the might of its six strong legs, each one tipped with a pair of needle-like tarsi, and that is precisely what this one did upon the first effort to brush it away. The dance our companion then executed was very much like the ones I imagine leprechauns must engage in: sort of a hornpipe, with much leaping through the forest from one foot to the next, hysterically swatting his own crotch. We maintained him in our flashlight beams until he disappeared into the jungle. A few moments later he emerged...alone, and a better man, if only for that evening.
This summer, residents of Utah's Wasatch Mountains have been treated to an unusually high number of our largest native beetle, the Giant Root Borer (Prionus californicus).
Reaching three inches in length, this rufous behemoth really is spectacular, and ordinarily rare enough (an average summer sees no more than one or two) to make catching one an event. So far, 2007 has yielded seven. Immediately upon their capture they effect a very loud and charming scraping sound, which is common to many big beetles, although the exact mechanics of it I’ve never been able to divine. A pair of powerful mandibles mandates some degree of care in their handling. As the name implies, the grubs fed on the root crowns of Gambel’s Oak (Quercus gambelii). In some parts of the American West these grubs were said to be an important food for certain Indian communities, although I can't imagine how they located them. I'm equally puzzled by the number I've seen this year. Does it reflect the decline of an important predator? A beneficial environmental change? Or a statistical anomaly? Perhaps further observations will yield some answers, but for now I'm all questions.
upper: STILL LIFE WITH BEETLES (2000) acrylic 20" x 26" The large beetle with maroon elytra in front of the book's spine is a Great Goliath Beetle (G. goliatus). Directly above the tip of its snout, a Giant Root Borer comes in for a landing. In the loser right corner is a Hercules Beetle.
lower: Photo of a road-killed Giant Root Borer taken by CPBvK July 26, 2007