river talk

Springtime predator: the tiger beetle

By SCOTT RANDO
Posted 5/20/20

I remember walking down an access road on state game lands a few years ago. It was a nice day around this time of year. The birds were actively calling; some of them could be seen as the leaves had …

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river talk

Springtime predator: the tiger beetle

Posted

I remember walking down an access road on state game lands a few years ago. It was a nice day around this time of year. The birds were actively calling; some of them could be seen as the leaves had not really started to grow on the trees yet. The road was not well used this time of year, and I always checked wheel rut puddles for frogs and generally kept my eye open for anything that would cross the road or the cleared area around it.

Enter the springtime predator: the six-spotted green tiger beetle.

On the ground in front of me was an iridescent green beetle, a real eye-catcher. As I watched it walk, I noticed it was fast, and it was hard to follow in flight as it was pretty small. It flew a couple of times, landing a few feet further down the road. It seemed to prefer the sand or other clear areas of road, away from the grass that was in many areas. I saw a few of these on the road as I walked. Observing their speed on the ground, I got the impression that these beetles were efficient predators, even with their easy-to-see iridescent green color. There are 147 different species of tiger beetle, but this one, with its conspicuous metallic green, is the prevalent one in the region.

The six-spotted green tiger beetle also has six yellowish spots on the back of its elytra (the hard wing covers of beetles). Some individuals may have fewer spots or no spots at all. The six spots are rarely noticed as this beetle typically moves quickly and erraticly. Its speed helps it to capture insects on the ground after its large eyes sense movement by unsuspecting victims. After a brief spurt of speed, the tiger beetle has its prey in its formidable mandibles. This predator can catch insects many times its own size; the six-spotted green tiger beetle measures at around a half-inch.

Tiger beetles live for two years; females lay eggs singly in burrows during late spring to early summer. The egg hatches and the larva, which resemble caterpillars, stay in the ground with its oversized head at the ground’s surface. The larva is equipped with large mandibles to capture passing insects. Hooks on its abdomen keep it anchored in the burrow in case the prey the larva clamps onto is a bit more than it can chew. It will overwinter in the ground, and next spring, the pupa stage of this beetle digs it way to the surface to emerge within a month. The adult form of the tiger beetle repeats the lifecycle in the spring. After breeding and egg-laying, adult beetles die during the summer.

So, the next time you’re walking on a sandy or loamy trail, or a dirt road that’s not too busy, take a look for these creatures darting quickly back and forth with their long legs—then take an even closer look. It may be the green chrome version of the “Electraglide in Blue” beetle. Approach slowly, and you may get a good look at this iridescent springtime predator.

tiger beetle

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Steve Johnston (Callicoon)

"Predator" is a term that usually has negative connotations. Yes, the article does mention "insect predator" in passing, but I fear that a casual reader might miss the point that the six-spotted green tiger beetle is a "good" (welcome) predator.

--A fascinating and informative (if slightly podding) article.

Monday, May 25