outdoors
A six-spotted tiger beetle.
Tigers in the sandbox Story and photos by Scot Stewart
T
hey hunt by day, right under your feet. With bulging eyes and big jaws, they’re ready to chase down and pounce on an unsuspecting ant or other small insect wandering along a sunny dune or open, sandy bank. They are Tiger beetles, one of the most interesting, colorful groups of beetles. Beetles are the largest group of living things on the planet and belong to the division or order of insects called Coleoptera. So far, more than a quarter million beetles have been named, which is about 1/5 of the 1.2 million living species known named and identified to science so far. And while the numbers change all the time, other numbers (like 8.7 million, using diversity pattern estimates) are widely recognized as a starting point toward the truer number. Still, the number of beetles is impressive, and the diversity of tiger beetles is, too. At least 100
different types are found in the United States, and worldwide. There are more than 2600 different kinds of tiger beetles. These are small dynamos, most between half and three-quarters of an inch long. Because of their size and their take-flight behavior when startled, they are rarely noticed. They can also run extremely fast. (More about that later.) Most live in the tropics, but more than a dozen species live in Michigan. The best places to look for them are in sand dunes, along sandy trails and in sparsely vegetated dry areas. Around the world, most live on the ground, but in tropical areas some live in trees. Tiger beetles are incredibly colorful. Some have entirely bright green exoskeletons, while most in the U.S. are brownish with calligraphic markings on their back and amazing hints of metallic green, violet and purple across
their bodies and legs. Some also have lots of hair-like structures across their mid-section, or thorax, and legs. Their markings help camouflage them on the sand and among the dried parts of plants so well that even after watching one land, to look away for a minute means probably losing it in the mix. Some of the tropical species look like they have been splashed with the best metallic paints ever used on race cars, but can still blend in, matching sunspots, flower petals and other bright, colorful dabs of light and life among the ground cover. Tiger beetles are insect eaters. They feed mostly on ants, insect larvae and spiders, but will hunt just about anything small enough to catch. Their eggs are laid in the ground, and the young larvae dig a tunnel up to 2 feet down where they live. These immature beetles hunt by coming to the surface and waiting for prey to wander by.
September 2021
Marquette Monthly
29
