the ultimate crevice bug

April 12, 2006

in Insects,Natural history

This week I’ve been trying to finish up some especially obnoxious paperwork on a project before my field season begins in earnest.  Since I’m annoyed, I thought I’d take a little break and write about an annoying creature: the earwig.

I find earwigs just repugnant.  I don’t know why. While not attractive, they are less disgusting-looking than any number of other invertebrates that I don’t find objectionable.  Despite the ominous curving cerci (the forceps-like abdominal appendage), they are harmless.  The story that they get in your ears and bore into your head is an old wives tale.

There are several species of earwig in Michigan, but the most common is the European earwig, Forficula auricularia, a non-native species (I hesitate to name the other another exotic earwig found here, for fear of the Google traffic it will bring me, but, what the hell — it’s Labia minor).  European earwigs were introduced into North America around 1912, and they are now pretty ubiquitous in gardens and just about any other humid, mulchy place across the eastern U.S.  Their nastiest habit in my garden is rose petal munching.  All in all, pretty benign.

An old Michigan earwig fact sheet noted: “European earwigs can be kept in captivity with a minimum of care. Although few people are fond of earwigs, they can be interesting to watch and easy to care for.”  In the interest of full disclosure, the author of this page is a good friend of mine, and as such is pretty offbeat.  Still, I didn’t think he was so strange as to recommend earwig husbandry.

Turns out that observing earwig family life, while not gripping, is at least a mildly intriguing. Females clean, rearrange, and defend their eggs.  For a short period, she will also bring food to the young nymphs, or regurgitate food for them.  These behaviors are fairly unusual in a non-social insect.

I’d be remiss writing about earwigs without mentioning the world’s largest species, at nearly 3.5 inches, the endangered (or extinct) Labidura herculeana. It is endemic to the U.K. island of St. Helena, where Napolean Bonaparte spent his last years in exile. The last live St. Helena’s earwig was seen in 1967, but a piece of cerci was found in 1995, at which time St. Helena produced its second earwig postage stamp, shown here.  For you topical stamp collecting fans, there have been, somewhat remarkably, at least seven earwig stamps issued in the world, awaiting placement in your album.

Several further searches have failed to find any living L. herculeana on St. Helena. Like many islands, it has a high rate of endemism, including 49 endemic plants, 13 ferns, 400 invertebrates (check out the St. Helena spiky yellow wood louse), and 6 birds, only one of which survives today — the St. Helena Plover, a.k.a., Wirebird.  The unique flora and fauna have suffered from habitat destruction and introduced animals. In the case of the earwig, it is presumed that habitat loss, predation by rats, and competition from the introduced giant centipede Scolopendra morsitans contributed to its demise.  To add insult to injury, the struggling island endemics are now threatened by a new airport.  UPDATE: In late 2014, the St. Helena earwig was officially declared extinct.

My break time is over, and I’ve succeeded in not only distracting myself from my aggravating paperwork, but my venting has led me to a grudging appreciation of the order Dermaptera.  Although I still think they’re gross.

Image: Wikipedia Commons.


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