Last week on a sunny afternoon, a busy ensemble of stink bugs, lady beetles, and other insects ambled about the siding of a white farmhouse along the C & O canal in western Maryland. Among the most interesting of the gang was a five-legged, leaffooted bug. Let’s start with the business of the identity of a leaffooted bug. Leaffooters belong to an insect family called Coreidae, members of order of insects named Hemiptera. These ‘true bugs’ have sucking mouthparts, two pairs of wings, and immature feeding stages called nymphs. More familiar members of this clan include stink bugs, squash bugs, and assassin bugs we’ve met in previous episodes. Leaffooted bugs are so named for the remarkable leaf-like ornamentation on their hind legs. Leaffooted bugs are herbivores, consuming plant tissues as juveniles and adults.
Leaffooted bugs here in the DMV sport impressive flags on their hind legs.
Ok, what’s so cool about a leaffooted bug, especially one with five-legs? First, what in the world are those fantastic leaf-like structures on the hind legs for anyway? Some male relatives of the leaffooted bugs we visit today have mighty, enlarged hind legs. These powerful legs, termed “sexual weapons”, are used to battle other males for mating territories and access to females. A second, and perhaps more fascinating purpose, is to direct a potentially lethal attack by a bird away from a vital body part like the head, to a less critical body part like a showy or colorful flag on the hind tibia of the bug. A fascinating study by Zachary Emberts and colleagues found that several members of the leaffooted clan had evolved the ability to drop a limb (= autotomy), to avoid death or entrapment by predators. This induced “loss of a leg” results when the femur of the upper leg detaches from a small segment called the trochanter near insect’s body.
Watch as a five-legged leaffooted bug ambles along a railing on a bridge. Several members of the leaffooted clan have evolved autotomy, the ability to drop a limb under dire circumstances like a predator attack. The showy flag on the hind leg likely directs a potentially lethal attack away from a vital body part like the head, to a less critical part like a leg. As the leaffooted bug takes flight, it looks like it is better to lose your leg than lose your life. And what are those two white spots on the back of the bug? Tune in to another episode to find out.
How common is leg autotomy? In their study of wild coreids, Embert’s et al. found autotomy to occur from 7.9% to 21.5% of the time in the species examined. While dropping a leg to save a life might sound like a good idea, there is a hitch. Recall that male leaffooted bugs may use legs to battle other males for access to a mate. Males missing a leg may lose out in the mating game. Lose a leg and lose a mate vs lose a leg and save your life. I know what I’d do. How about you?
A gaggle of leaffooted bug nymphs dines on a pumpkin vine.
Acknowledgements
Bug of the Week thanks Dr. Shrewsbury for helping with wrangling and spotting leaffooted bugs. The fascinating article “Coreidae (Insecta: Hemiptera) Limb Loss and Autotomy” by Zachary Emberts, Colette M. St. Mary, and Christine W. Miller provided valuable insights into the lives of leaffooted bugs and the evolution of autotomy.