Each Wednesday, my family receives a carefully packed box of veggies from a local farm. We spend the rest of the week trying to figure out what to do with them. With each batch of greens, there are a few extra surprises that come to us free of charge. Almost every time we peel the outer leaves from one of our cabbages, an earwig leaps out and scurries across the kitchen counter. Our 6-year-old daughter, Anna, asked me to write about earwigs for my next blog, so here goes.
What makes earwigs so recognizable, and scary to some, is their backward-facing pinchers. They use these tweezers (technically called cerci) mostly to capture prey and intimidate predators. Although they look menacing, the cerci are totally harmless to humans. Earwigs cannot sting and will not bite us.
There are about 20 species of earwig in the United States. Most of them were accidentally introduced from other countries. Some of them prefer warmer climates than we enjoy here in the Lehigh Valley. Our native earwigs generally spend hidden lives along beaches or riverbanks. Earwigs have been around for roughly 208 million years, mostly off the radar scope of humanity. They evolved from an insect that is now extinct but probably looked a bit like an old fashioned cockroach.
By a landslide, the European Earwig (Forficula auricularia) is our most common species of earwig. About one century ago, they were discovered in the Pacific Northwest and in Rhode Island at about the same time. Whether they hitchhiked from one coast to the other, or were coincidentally introduced to both places from Europe at some point between 1907 and 1915 is not known.
According to a delightful 1924 treatise by B.B Fulton on the European Earwig, the insect “gained fame by making itself obnoxious.” Reality TV is nothing new! The recommended treatment for European Earwigs in 1924 was a mixture of molasses, what bran and sodium fluoride or arsenic. Heavy weaponry indeed.
The European Earwig is the only earwig species that is likely to look for shelter in our homes. According to experts at Penn State, indoor earwigs can occasionally become a nuisance and may release a pungent perfume when disturbed. In this way, they resemble the Brown Marmorated Stink Bug, another potentially fragrant and usually uninvited house guest.
Like our famous Brown Marmorated Stink Bug, European Earwigs have spread throughout North America, especially the cooler and wetter parts. When they first arrived, they caused quite a sensation. In 1924, the City of Portland, OR, declared a state of emergency and established a Bureau of Earwig Control. Since that time, Portlanders have found other things to worry about. Part of the concern probably arose from the mistaken notion that earwigs transmit human diseases. They don’t.
Early accounts document the European Earwig as a serious nuisance pest. In some cases, it drove people from their homes. As a recent immigrant in the 1920s, the European Earwig had few natural enemies. Since then, tiny parasitic worms called nematodes, insect-killing fungi and parasitic flies have all played a role in curbing their enthusiasm. European Earwigs can still be a nuisance under some circumstances, but things are not as dire as they seemed in Portland, back in 1924.
Starting in the late summer, mom and dad European Earwigs work together to build a burrow below the surface of the ground. They will hibernate together over the winter. Sometime in early spring, before she lays a batch of eggs, the moms will kick the dads out of the nest. After a long winter, he must be pretty hungry. Her batch of 60-100 eggs would be a perfect snack for him.
The mother earwigs must be very hungry too, but she carefully guards the eggs from predators until they hatch. She only eats the eggs if they get moldy. This prevents the fungal infection from spreading to her other eggs. After the eggs hatch, the mother will protect them from enemies and feed them by regurgitating pre-chewed food. She keeps this up until the little ones have shed their exoskeleton for the second time. After that, it’s time for the kids to move away from the nest, before they become tasty treats for their hungry mothers.
According to Richard Hilton, an entomologist with an “inordinate fondness for earwigs” at Oregon State University, the claim that earwig are unusually wonderful mothers is a "mixed bag." Keeping things in perspective, many human mothers will often tolerate their offspring living in the nest long after they have graduated from college.
According to legend, earwigs will crawl into the ears of sleeping people and lay their eggs. This probably explains how they got their name. “Wig” is derived from the Old English word for a bug or “wiggler.” The "earwig larvae feeding on the brain" myth has been thoroughly debunked. However, earwigs do like to squeeze into narrow and dark spaces and have in rare cases become lodged in human ears. Much weirder things have been found within our collective ear canals. Bottom line: earwigs are no more common as “aural foreign bodies” than any other household insect.
If earwigs are still not your cup or tea, just be glad we don’t have the Saint Helena Earwig here in the Lehigh Valley. They measured up to three inches long! They have only been found on the remote South Atlantic island of Saint Helena (made famous by the exile of Napoleon in 1815). Saint Helena Earwigs have not been found since 1967 and the species is feared to be extinct.
European Earwigs don’t seem to be very picky about what they eat. They do draw the line before wood, which they cannot digest. They are particularly fond of aphids, which makes them at least partly a beneficial insect. Several studies have found European Earwigs to be effective in controlling wooly apple aphid infestations. Nevertheless, I would not expect them to be sold at the local garden center any time soon.
Home invasions by European Earwigs are generally the combined result of a favorable outdoor habitat and convenient entryways into the house. Sometimes when the weather gets very hot and dry, earwigs will seek the cool refuge of a basement or a garage. From the European Earwig’s point of view, the house is not a perfect place to be. Since they are omnivores, they are able to survive on pantry items and pet food. However I wouldn’t imagine our processed foods to be as wholesome to European Earwigs as fresh bugs and succulent vegetation. Since they need to build nests in the soil, they cannot reproduce in the house.
If your home has become a temporary earwig haven, consider taking a close look at the perimeter of the house. They love to burrow into narrow spaces and need moist and dark hiding places to spend their days, resting in advance of nocturnal adventures. Are there decomposing leaves, mulch, ivy beds, leaky drain pipes, piles of empty flower pots, newspapers or other earwig hiding spots in contact with the house? I wouldn’t use insecticides for an earwig infestation of my home. A little bit of habitat management and some quality time with a caulking gun to fill up entry spaces would be more effective and less toxic.
In my garden, I usually find earwigs under flower pots. Of course I could not find any today because I was looking for them to take a photograph. They must be camera shy. The most that I have ever seen was in a bird house that a family or wrens had previously occupied. There must have been at least 50 of them, fastidiously cleaning up what the birds had left behind.
We look forward to our weekly box of veggies, each complete with its own batch of watchable wildlife. I like to think of earwigs as wiggly toxin detectors, letting us know that our fresh produce is probably not saturated with pesticides. Anna cheers them on as they frolic and romp about the kitchen. After that, we gently fling them into the backyard where they can pursue a new set of adventures.
This work by Marten Edwards is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.