Tiger beetles are stunning insects, with distinct markings and brilliant colors. They sit tantalizingly close, sunning themselves on wide forest trails or sandy beaches. But the moment you try to move in for a closer look, they're gone. Tiger beetles are among the fastest insects you'll ever encounter, making them difficult to photograph and even harder to catch.
How Fast Are Tiger Beetles?
Fast! The Australian tiger beetle, Cicindela hudsoni, was clocked running at a remarkable 2.5 meters per second. That's the equivalent of 5.6 miles per hour and makes it the fastest running insect in the world. Running a close second is another Australian species, Cicindela eburneola, which ran an impressive 4.2 miles per hour.
Even the relatively pokey North American species, Cicindela repanda, scampers at speeds reaching 1.2 miles per hour. That may seem slow compared to its brethren down under, but a Cornell University study found this tiger beetle runs fast enough to temporarily blind itself.
Cornell entomologist Cole Gilbert noticed tiger beetles tend to stop and go a lot while pursuing prey. It didn't make much sense. Why would the tiger beetle take a break, mid-chase? He discovered the tiger beetles were running so quickly, they couldn't focus on their target. Tiger beetles literally run so fast, they blind themselves.
"If the tiger beetles move too quickly, they don't gather enough photons (illumination into the beetle's eyes) to form an image of their prey," explains Gilbert. "Now, it doesn't mean they are not receptive. It just means that at their speed during the chase, they're not getting enough photons reflected from the prey to make an image and locate the prey. That is why they have to stop, look around and go. Although it is temporary, they go blind."
Despite being temporarily incapacitated, tiger beetles run fast enough to make up the distance and still capture their prey.
You might wonder how a beetle that runs so fast it can't see can manage to do so without bumping into obstacles. Another study, this time of the hairy-necked tiger beetle (Cicindela hirticollis), found the beetles keep their antennae positioned straight ahead, in a firm V shape, while running. They use their antennae to detect objects in their paths and are able to change course and run over the obstacle the second they feel it.
What Do Tiger Beetles Look Like?
Tiger beetles are often iridescent, with well-defined markings. Most species are metallic tan, brown, or green. They have a distinct body shape that makes them easy to recognize. Tiger beetles are small to medium in size, usually ranging between 10 and 20 millimeters in length. Beetle collectors prize these shiny specimens.
If you have the good fortune to observe one closely (no easy feat given how fast they flee), you'll notice they have large eyes, and long, slender legs. Their large compound eyes enable them to detect either prey or predators quickly, even from the side, which is why they're so quick to escape when you try to approach them. If you watch one carefully, you'll notice the tiger beetle may run and even fly from you, but it will usually land just 20 or 30 feet away, where it will continue to keep its eyes on you.
On closer examination, you will also see that tiger beetles have large, powerful mandibles. Should you manage to capture a live specimen, you may experience the power of those jaws, because they sometimes bite.
How Are Tiger Beetles Classified?
In the past, tiger beetles were classified as a separate family, Cicindelidae. Recent changes to the classification of beetles rank the tiger beetles as a subfamily of the ground beetles.
- Kingdom - Animalia
- Phylum - Arthropoda
- Class - Insecta
- Order - Coleoptera
- Family - Carabidae
- Subfamily - Cicindelinae
What Do Tiger Beetles Eat?
Tiger beetle adults feed on other small insects and arthropods. They use their speed and long mandibles to snatch their prey before it can escape. Tiger beetle larvae are also predaceous, but their hunting technique is quite the opposite of the adults. The larvae sit and wait in vertical burrows in sandy or dry soil. They anchor themselves with special hook-like appendages on the sides of their abdomen, so they can't be dragged away by a larger, stronger arthropod. Once in position, they sit, with jaws open, waiting to slam them shut on any insect that happens to pass by. If the tiger beetle larva successfully catches a meal, it retreats into its burrow to enjoy the feast.
The Tiger Beetle Life Cycle
Like all beetles, tiger beetles undergo complete metamorphosis with four life stages: egg, larva, pupa, and adult. The mated female excavates a hole up to a centimeter deep in the soil and deposits one egg before filling it in. The hatched larva constructs its burrow, expanding it as it molts and grows through three instars. The tiger beetle's larval stage may take several years to complete. Final instar larvae pupate in the soil. Adults emerge, ready to mate and repeat the life cycle.
Some tiger beetle species emerge as adults in the fall, just before the first frost. They hibernate during the winter months, waiting until spring to mate and lay eggs. Other species emerge in the summer and mate immediately.
Special Behaviors and Defenses of Tiger Beetles
Some tiger beetles produce and release cyanide when facing the imminent threat of being eaten by a predator. These species typically use aposematic coloration to give a friendly warning that they aren't particularly palatable. If a predator has the misfortune of catching a tiger beetle, it won't soon forget the experience of getting a mouth full of cyanide.
Many tiger beetle species inhabit extremely hot environments, like sand dunes and salt flats. How do they survive without being cooked on the hot, white sand? These species are usually white or light tan in color, which enables them to reflect the sunlight hitting their backs. They often also have hairs on the undersides of their bodies to insulate them from the heat radiating off the surface of the sand. And they use their long, thin legs as stilts to lift them from the ground and allow air to flow around their bodies.
Where Do Tiger Beetles Live?
An estimated 2,600 species of tiger beetles live throughout the world. In North America, there are about 111 described tiger beetle species.
Some tiger beetle species require very specific environmental conditions, which limits their ranges considerably. Their restrictive habitats put some tiger beetle populations at risk, as any disturbance to environmental conditions can imperil their survival. In fact, tiger beetles are so sensitive to such changes they are considered bio-indicators of environmental health. They may be the first species in a particular ecosystem to decline in response to pesticide use, habitat disturbance, or climate change.
In the U.S., three tiger beetle species are listed as endangered, and two are threatened:
- Salt Creek tiger beetle (Cicindela nevadica lincolniana) - endangered
- Ohlone tiger beetle (Cicindela ohlone) - endangered
- Miami tiger beetle (Cicindela floridana) - endangered
- Northeastern beach tiger beetle (Cicindela dorsalis dorsalis) - threatened
- Puritan tiger beetle (Cicindela puritan) - threatened
- Borror and DeLong's Introduction to the Study of Insects, 7th edition, by Charles A. Triplehorn and Norman F. Johnson.
- Beetles of Eastern North America, by Arthur D. Evans.
- Bugs Rule! An Introduction to the World of Insects, by Whitney Cranshaw and Richard Redak.
- "Chapter 39: Fastest Runner," by Thomas M. Merritt, Book of Insect Records, University of Florida. Accessed online January 31, 2017.
- "Subfamily Cicindelinae - Tiger Beetles," Bugguide.net. Accessed online January 31, 2017.
- "When tiger beetles chase prey at high speeds they go blind temporarily, Cornell entomologists learn," by Blaine Friedlander, Cornell Chronicle, January 16, 1998. Accessed online January 31, 2017.
- "Listed Invertebrate Animals," Environmental Conservation Online System, U.S. Fish and Wildlife Service website. Accessed online January 31, 2017.
- "Tough, Tiny Tiger Beetles," Arizona State University website. Accessed online January 31, 2017.
- "Static antennae act as locomotory guides that compensate for visual motion blur in a diurnal, keen-eyed predator," by Daniel B. Zurek and Cole Gilbert, in the Proceedings of the Royal Society B, February 5, 2014. Accessed online January 31, 2017.