Last week beneath a snowy log we met a colony of bess beetles awaiting the return of spring. Also, lurking in the dank and dark nearby was a ferocious predator, the larva of the eyed elater. The eyed elater, a.k.a the eyed click beetle, is a member of a large and economically important clan. Larvae of several species of click beetles are plant eaters. When they feed on the subterranean parts of crops such as wheat, corn, or potatoes, they can be noxious pests. Many click beetle larvae are meat eaters rather than plant eaters. The fierce larva of the eyed elater has powerful jaws used to disable and dismember victims. Prey commonly includes other insect larvae such as flies and, sadly, other beetles such as bess beetles.
The spine and notch are part of the engineering that give this beetle its click.
Why the name "click" beetle? If captured by a predator like a bird or by an entomologist who might flip it on its back, the click beetle is able to produce an unnerving snap of its body that rights it and produces an audible click. Click beetles have a remarkable spine on the undersurface of the first segment of the thorax. This spine fits into a notch on the second thoracic body segment just between the legs. The beetle flexes its body in such a way that the spine quickly releases or snaps with a click. When placed on its back, this snap can catapult the beetle in the air. The beetle often lands right side up. If the beetle lands on its back again, the process is quickly repeated until the beetle gets it right. This is wickedly amusing, but should be discontinued if the beetle protests. Why the beetle is called the eyed elater is easy to understand by taking one look at the adult. It has two large crazy "eyes" on the back.
False eyespots may help the eyed elater look scary to predators.
These are not real eyes, not ones used for vision. The true eyes are on the head of the click beetle near the base of the antennae. False eyespots such as those on the eyed elater are common in many species of insects including moths, butterflies, and caterpillars. The eyespots are thought to startle or confuse predators such as birds or reptiles that might want to make a meal of a tasty beetle. Smaller less dramatic click beetles will be frequent visitors to our porch lamps later in spring and summer. They are great fun to capture and most entertaining. Please put them back unharmed when you are done.
References:
For more information on click beetles and the eyed elater, please visit the following web sites.
http://insects.tamu.edu/fieldguide/bimg151.html
http://www.umassturf.org/mangement_updates/2005_archive/05sep16.html