A distinct advantage of working with the public as a biology instructor is having an unending pile of "What is it?" items deposited at my doorstep. Animals, vegetables, minerals, and even corpses (non-human) in varied states of decay, inevitably find their way to my mailbox or are hand-delivered by curious friends and strangers. Whatever the parcel's contents or the method of delivery, the enthusiastic courier is always certain to exclaim, "You won't believe what I just found!"
In particular, and in what has become a rite-of-summer, I am presented annually with a covered container and the solemn warning,: "Careful, it really jumps." From within the container a peculiar rattle is heard; "it" is knocking randomly against the walls and ceilings of the makeshift cage. The distinctive snaps and clicks have become familiar to me by now, and with confidence I release one of our most remarkable native insects - the big-eyed click beetle.
Although common, click beetles are not often chanced upon. Most frequently they are discovered on a lighted porch in the evening, or soar through an open window as uninvited house guests. Harmless, they nonetheless create a stir with their unexpected and sometimes ominous appearance. Click beetles are equipped with two menacing "false eyespots" on the thorax, and many are more than 1-1/2 inches in length. Understandably, people are discouraged from rushing to pick them up.
Click beetles also process a secret weapon which is guaranteed to startle both naturalists and predators alike. When threatened, a beetle's first line of defense is to release its grip from what it is climbing on, drop to the ground, and lie motionless and upside down until the danger passes. (This is typical of most beetles, and gardeners are well aware of this strategy if they have ever done battle with the Colorado potato beetle.)
However, instead of playing dead as its cousins do, the click beetle arches its body and launches itself repeatedly into the air with an audible "click." Often it jumps as high as six inches. When it feels secure, the beetle scurries off to safety. Predators may well be intimidated by this frantic behavior, although as you might suspect, cats find it rather entertaining.
Click beetles are primarily vegetarians, feeding
on roots and tubers. Some of the
Tropical relatives of the big-eyed click beetle are called fire beetles and have bioluminescent eye-spots. One, Pyrophorus luminosa, produces "cold light" that is green and red, and is as bright as that of the more familiar fireflies. Its larvae, called glow-worms, also produce light.
There are many other less spectacular types of click beetles - about 8,000 species worldwide. Most of those in our region are smaller ands less striking that the big-eyed, but all have the distinctive clicking mechanism. Search for them on summer evenings - they are often found with other insects that collect around your porch light!
Big eyed click beetles and "wireworm" larvae. By forcing the thoracic spine on its underside into a resistant socket in the abdomen, a sudden snap results. This miniature shock wave passes through the body to the wing covers and the resultant force launches the beetle into the air.
In their Lilliputian world, the oversized eye-spots suggest a creature larger and more menacing than the harmless click beetle. Perhaps to a hungry predator, the jumping beetle looks serpent-like and dangerous as it snaps and rears up when threatened.