Sometimes, things don’t click...
...but they could. This animal is a type of click beetle. Click beetles are in the Family Elateridae, a family that has over 9000 species world wide. This particular click beetle (Elater lecontei) doesn’t have a common name, though it is rather large (nearly 30mm). The species name “lecontei” comes from the Greek word for plate or dish “lekos”.
Click beetles have a fascinating behavior for righting themselves on smooth surfaces. Unlike most beetles, click beetles have a flexible joint between the first and second thoracic segments (between the first and second pairs of legs). There is a spine (prosternum spine) on the bottom of the forward segment.
When the beetle is placed on its back on a smooth surface, it will arch its back till the spine slips into a catch on the second segment. The beetle then pulls hard with its muscles to straighten out, but the spine prevents the beetle from bending and stores a lot of elastic energy. Eventually, the spine slips off the catch with an audible click and the beetle is flung into the air up to 30cm. Typically the larger the click beetle, the less high it can "jump". If it lands right side up, it wanders off about its business. If not, it repeats the process again.
The beetle undergoes a huge amount of acceleration when it “jumps” (on the order of 400g). This is a lot of acceleration. The maximum acceleration in a fighter plane doing extreme maneuvers is a bit over 10g, so this nearly 40 times what a pilot would experience. The click beetle acceleration is over very quickly: less than 0.5 milliseconds. The beetles muscles can’t contract that fast, so they can only “jump” by storing the energy in the elastic catch system and explosively releasing that stored energy.
Of course, leaping like that is sort of blind faith, since you don’t know where you are going to land. Given a chance (and a rough surface like a rotting downed tree) the beetle will reach out with its legs and try to hook its “feet” to pull itself over. That’s what happened with the one I found.
In this picture of the beetle on its back you can see the prosternum spine extending behind the first pair of legs on the mid line of the body.
Here it’s hooked the “feet” of its first and second right legs on the rough tree trunk and has is turning over the old fashioned way.
Nearly back on its feet in this picture.
Click beetles will also do the clicking motion if you hold them between two fingers. The “click” and snapping feeling is supposed to startle you and make you drop the beetle. I suspect its pretty startling if you pop it in your mouth and it “clicks”.
This click beetle was found under a rotting log along the Santa Margarita RIver near Temecula, CA, which is about 1.5 hours north of San Diego.
Most click beetles feed on plants as adults. The tough click beetle larvae look like long, thin mealworms and are called wire worms. Wireworms are usually found in rich soils or decaying wood where some species feed on fungi, others on small insects and some (which can become agricultural pests) feed on roots.
References
Schmidt-Nielsen, N. (1981). Animal Physiology: Adaptation and Environment. Second Edition Cambridge University Press, Cambridge, United Kingdom.
Evans, A.V., and Hogue, J.N. (2006). Field Guide to Beetles of California (California Natural History Guides). University of California Press, Berkeley, CA.
Brown, R.W. (1956). Composition Of Scientific Words : A Manual Of Methods And A Lexicon Of Materials For The Practice Of Logotechnics. Smithsonian Institution Press, Washington, DC.
