Like other beetles, tiger beetles have shell-like wing covers (elytra) over the abdomen, and a shieldlike pronotum between the head and elytra. The shape of tiger beetles is distinctive: The elytra sides are parallel, or widen slightly toward the hind end; the pronotum is narrower than the elytra, looking something like a neck, and the bulging eyes make the head wider than the pronotum. The mandibles (mouthparts) are large pincers, and the antennae emerge just above the base of the mandibles. The legs are long and skinny. Color can be black, brown, or green. Many species are iridescent or have bright spots or other color patterns. Their fast-running and fast-flying behavior is another way to identify them.
The larvae, sometimes called doodlebugs, are pale or tan and grublike, with six legs, and have strong pincers at the mouth. There’s usually a hump behind the rather large head. They dig holes down into the ground and rest near the entrance.
Similar species: The larvae of antlions are also (and more commonly) called doodlebugs. They usually live in sandy or dusty substrates and make little conical depressions, which they live at the bottom of, just under a layer of dirt.
Length: most are ½ to ¾ inch, though some North American species reach 2 inches (varies with species; does not include appendages).
Habitat and Conservation
If you see an iridescent beetle land suddenly before you on a trail, pause, then flash away, you’ve probably seen a tiger beetle. Stupendously fast runners and fliers, they are notoriously hard to capture. They’re usually seen in open areas, especially with dirt or sand substrates, including dirt trails, gravel roads, sandbars, and the borders of streams and other bodies of water. Some are nocturnal; others are most active during the day. The larvae build vertical tunnels deep in the soil.
Both the larvae and adults hunt other insects. The larva digs a burrow, then waits near the surface, where it can grab other insects that walk by. The adults fly or run down their prey and can therefore capture both walking and flying insects.
Females lay eggs singly into shallow holes in the soil. Upon hatching, the larva creates its burrow at this site. Like other insect larvae, they eat, grow, molt, and grow. Depending on species, it can take 1-4 years before they pupate and become adults. In some species, adults emerge in fall, hibernate in winter, and mate and lay eggs in spring. In other species, adults emerge in late summer, mate, and lay eggs, which hatch in fall. In these species, it’s the larvae, not the adults, that overwinter.
Because they hunt other insects, many people classify tiger beetles as “helpful.” Biologists find them helpful, in another way, since the very presence of tiger beetles provides valuable information about the ecological health of an area. If you handle them, be careful, since they can pinch you hard.
As predators, tiger beetles help maintain the natural balance of insects in an ecosystem. Although few predators are fast enough to capture adult tiger beetles, the larvae and eggs are vulnerable to predators ranging from grackles and moles to sandpipers and skunks.