Meet the Nightmare Bug

focus on nature Warning: This Bug May Scare You Silly (It's Arizona's Largest Horned Beetle)

The first time I saw a H Hercules beetle, a lurid corner of my imagination flashed back to a nearly forgotten grade-B horror movie. You know the type; their titles give them away: Bug, The Fly, Tarantula, The Swarm. And the plots are strikingly similar: Some really scary-looking insects suddenly mutate to gargantuan proportions and swarm into Los Angeles or Chicago to inflict havoc and terrorize the population. Crushing buildings, flicking tractor-trailers off freeways, setting fires, the monsters rampage until scientists devise a way to stop them, just in the nick of time.Our fear of insects is deepseated. Maybe it's because there are just so many of them. Worldwide, well over 1 million species of insects are known, and some experts believe there might be 10 times that number. Of the known species, beetles which range from the smallest to the largest insects are the most numerous, making up 125 different families and approximately 500,000 species. My Arizona variant of the Hercules beetle, named Dynastes granti, is one of three species of horned beetles living in the Southwest. Although not the largest of the so-called rhinoceros, aka horned, or H Hercules beetles, it is the biggest in Arizona and a favorite among collectors, not only for its size but also for its shape, color, and two rather intimidating horns.

The thick-bodied male Hercules beetle, larger than the female and sporting a pair of impressive horns, can be up to three inches long and more than one and a half inches across the back. It belongs to the family Scarabaeidae, a group that includes some of the most dazzling colored beetles, some having metallic gold or silver pinstripes and bright-blue or green feet. The Hercules is a beautiful insect. Its elytra, the forewings which fold back across the length of its body, are the color of putty or pewter, polished to a slight sheen. Random brown dabs sprinkle the gray, highlighted here and there with threadlike brown striations. In some individual beetles, dark spots and streaks cover so much of the body that the insect appears entirely brown. In others an entire forewing may be brown while the other is spotted. Much like the rhinoceros, its namesake mammal, the male Hercules beetle has a pair of opposing horns, one curving upward from its prothorax, the other jutting unicornlike from its head. The horns are splendid for, like the beetle's six legs, they appear to be enameled in shiny black with an inner lining of soft amber. Although appearing rather clunky in repose, the Hercules beetle flies, using a pair of wings which, when not in operation, are covered by the forewings. Although not actually used in flight, the leathery elytra may act as airfoils, aiding navigation. When on the wing, the H Hercules beetle makes a loud whirring racket. The first one I saw droned loudly for several minutes. For all their apparent menace, the horns of the Hercules beetle seem intended for mating display. In competition for females, the "bull" with the biggest rack usually carries the day. Rarely are horns locked in actual battle with another male beetle. If molested, the rhino beetle's first line of defense is to squirt a tobacco-colored fluid from the tip of its abdomen. If that does not discourage an intruder, the beetle is likely to simply fly off rather than bite or try to use its horns in selfdefense. Although many beetles are carnivores, some of them even fiercely predatory (the ladybird beetle for example), the Arizona Hercules beetle is a vegetarian, preferring the cambium or inner layer of the bark of velvet ash trees that grow along wash beds. Beetle larvae feed on rotting wood, again preferring that of the velvet ash. Oh, and those giant monster beetles in the horror films. Forget them. It can't happen. In fact, all of the nightmare monsters rendered in mutantinsect horror films are physically impossible. Like all insects, our beetle is held together by an exoskeleton, a hard shell. To grow it has to molt, shed the old skin, and wait for a new cuticle to develop and harden. The force of gravity would cause even a beetle the size of a Volkswagen Bug to collapse of its own weight before its new exoskeleton could harden.