The insect order Coleoptera, the beetles, dominates Earth’s biodiversity. Approximately one out of every three animal species is a beetle and about one out of every four species – including all plants, animals, and fungi – is a beetle. The preponderance of these small, often-armored insects led J. B. S. Haldane, a British geneticist and evolutionary biologist, to comment that “God has an inordinate fondness for beetles.” Beetles populate nearly every environment and every nook and cranny on Earth.
Our Sky Islands region boasts a true wealth of these tiny jewels, some of which are colorfully spectacular – such as metallic wood boring beetles. Among their ranks lurk covert terrorists, living lanterns, ones that battle over poop, and even a species that might lead to profound military innovations. But given that there are legions of other types of insects afoot, what exactly makes a beetle a beetle?
Let’s begin with the jaws. The vast majority of adult beetles possess jaws with mandibles that chew from side to side. Any intrepid school kid or naturalist has instantly felt this truth when ill-advisedly handling a larger species of beetle. OUCH!
Most adult beetles possess two sets of wings – a pair with which to fly that are delicate, translucent, and folded under the outer wing covers like parachutes, as well as the outer covers themselves, termed elytra.
Young beetles start life as a maggot-like larva that undergo complete metamorphosis into an adult. First an egg is laid, then a larva – whose function is to eat and grow – emerges, which eventually forms a pupa, which in turn transforms into an adult. Adult beetles are all about mating with just enough feeding to eventually reach life’s reproductive finish line.
Monsoon season is prime time for finding and observing beetles, as many species come out of the proverbial woodwork during this wet, fecund time.
One of my favorites is the bombardier beetle. We host a number of local Sky Island species, their title bestowed upon them owing to the startling chemical explosions that they use to deter would-be predators. Generally, species are fairly small, measuring well less than a half inch. The thorax and head often have a bronze hue, while the abdomen is blackish. This posterior segment is where two internal chambers cloister two distinct chemicals that can be purposely brought together by the beetle when it feels sufficiently menaced. A slick naturalist trick is to gently touch a bombardier beetle, eliciting a rapid explosion – easily seen (a puff of smoke), heard (a distinct squeak), and even felt (registers about 212 degrees F). All in all, a bizarre beetle.
Anyone that grew up in wetter environments in the U.S. is likely familiar with fireflies, which you may have just guessed are beetles. We have a few local species, only some of which produce chemical light. These “flasher” species come out during monsoon season, each flashing a specific light code evolved to attract a mate. This is light produced by bioluminescence, which is chemical light produced in a specialized organ.
Luciferase, an enzyme involved in the process, is sometimes used in forensics work to detect blood. The Lucifer connection may trace back to one meaning of the name, which is “morning star” – a clear reference to light.
The name “dung beetle” leaves little room for doubt as to the lifestyle of these beautiful, sometimes iridescent scarab beetles. Some were revered by ancient Egyptians, as they helped to sanitize cities. The moisture of monsoon season keeps scat wet enough for various dung beetle species to gear into action. These beetles fly slowly in search of dung, which is detected by scent. Once located, males of some species fight to roll a ball out of the fresh dung, sometimes with help from their mate. The pair sequesters their fetid prize in a discreet location – dung beetles are notorious poop thieves – where eggs are laid within the fecal ball. Let’s hope reincarnation is a figment of our imagination!
We end with another aptly named set of species – the whirligig beetles. These mostly aquatic insects earn their moniker by wildly gyrating atop areas of slow water, such a ponds and pools in streams. There they use the vibrations that they generate to find hapless invertebrate prey trapped on the surface of the water. Half of each eye peers above the water, while the other half sees below the water. If threatened, they can easily dive underwater or fly away. No doubt various countries are closely studying the military implications of these aerial, aquatic, and submersible beetles. Only in the beetle world!
Vincent Pinto and his wife, Claudia, run RAVENS-WAY WILD JOURNEYS LLC, their Nature Adventure & Conservation organization devoted to protecting and promoting the unique biodiversity of the Sky Islands region. RWWJ offers a wide variety of private, custom-made courses, birding & biodiversity tours. Visit: www.ravensnatureschool.org