Striped Earwig Vol. 9, No. 13
Labidura riparia
Family: Labiduridae
Order: Dermaptera
If not for their pinchers, earwigs would be rather mundane-looking insects, but as we will see, there is a lot more to earwigs than pinchers. Both males and females have pinchers, though those of males are usually a bit larger and more curved. Also known as cerci, the pinchers are used for capturing prey and for defense, and they can wield these quite deftly by curving their abdomen over their back and from side to side to grab and subdue prey.
Most earwigs are omnivorous and although they are sometimes viewed as pests—when they wander into homes as “occasional invaders,” and when they occasionally chew on plants, causing minor cosmetic damage, some species are somewhat beneficial. Striped earwigs are generalist predators that eat most any other smaller insect in their habitat. This can even include nymphs of their own species, but caterpillars and insect eggs constitute much of their diet.
Dermaptera is one of the smaller insect orders, with only around 2000 species worldwide, but we have several species here in the South. Some species are completely wingless, while others, such as this striped earwig, can fly. But wait, you may say, those wings are too short for flying! This is one of the most interesting things about earwigs—the way they fold their wings. The pinchers are cool, but their wings are amazing.
The leathery forewings you see in the photo are like the elytra of beetles. They are only for protection of the hind wings and are not used in flight. The fine, membranous hind wings are folded underneath using a complex design. Imagine a Japanese fan that is fanned closed, then folded upon itself, then folded again, and you have an oversimplified view. This question of how earwigs fold their wings has been well-studied by scientists, both biologists and engineers, including biomimicry engineers, but one of the best resources for understanding this better may be to check out this video on how to build a papercraft earwig . This is a great project for a budding young biologist—or origami enthusiast.
Female earwigs are better mothers than most insects. Not only do they establish a protected brood nest in which to lay their eggs and guard them while they are incubating, but they also care for the new hatchlings for the first several days of their life by leaving the nest to search for food and bringing it back to the young.
One final peculiarity of earwigs is that in some species, including striped earwigs, the males have two penises, though usually only one, usually the right, is used. However, scientists studying this peculiarity have determined that, at least in some species, if the primary penis is broken off during mating, which sometimes happens, the spare can be used in subsequent matings.
Next time you spot an earwig while doing garden chores, pause and consider; they are not as drab and uninteresting as you may have previously thought.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
The information given here is for educational purposes only. Always read and follow current label directions. Specific commercial products are mentioned as examples only and reference to specific products or trade names is made with the understanding that no discrimination is intended to other products that may also be suitable and appropriately labeled.
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