Kelly’s Field Notes
Common Name: Earwig
Order: Dermaptera (Greek for “skin wing”)
Family: 15 families within this order!
Genus: There are 42 genera of earwigs.
Species of Note Near You (There are 2,000 species of earwig! 25 occur in North America and 45 in Europe):
.European earwig (Forficula auricularia) - though likely here longer, the first recording of this species in the U.S. was in Seattle in 1907. The tachinid fly Bigonicheta spinipennis was imported in the 1920’s to control the European earwig population.
In northern North America the native is the spine-tailed earwig (Doru aculeatum).
Other species of North American earwig belong to the genera Forficulidae, Spongiphoridae, Anisolabididae, and Labiduridae.
Hemimerus talpoides live on the underside of African giant rats (Cricetomys gambianus). They are blind and wingless and feed on the rat’s dead skin and any fungi attached to the host as well. Arixenia emu has a similar relationship with bats.
The largest earwig, the St. Helena earwig, was a biggie! These earwigs grew up to 7.6 cm (3 in) in length! They were only found on St. Helena Island, but have not been seen since 1967. Researchers believe the possible reasons for their extinction are introduced predators, habitat loss, and the collection of the stones they lived under.
Earwigs have 1.6 cm long (0.6 in) flattened bodies and are sexually dimorphic, meaning the males and females differ in how they look. Males have curved, stout cerci (pinchers) while females have long thin cerci. The cerci are used to protect the earwig and to hold prey. They are mostly active at night, preferring to hide during the day and more so during the Summer months. They do not cause damage to homes or food and prefer to spend their time when indoors in dark, confined, damp areas.
Their name derives from Old English ēare (ear) and wicga (insect or beetle) or eard (soil) wicga. It maye come from an old wive’s tale that they enter our ear canals (they don’t intentionally, no more so than other bugs) or from their hind wings which resemble a human ear when unfolded.
Earwigs go through incomplete metamorphosis: egg, nymph, adult. You can tell adults and nymphs apart because adults are missing the ecdysial line (the line down the center of a nymph which splits when they molt) and adults have wing buds. Females lay eggs in Spring and Summer, between 50 to 90 eggs at a time. The females will tend to their eggs, cleaning them and defending them from predators. She may also eat a few from time to time if she is taking care of foreign eggs as well. When removing fungi from the eggs she also coats them in an antifungal chemical. That’s right! These mommas are so intense that if you give her eggs that are not hers she will also take good care of them as well. Once the eggs hatch, in about a week, she then tends to the nymphs. The mother will feed and groom them until their second or third molt, then they are on their own in about 40 to 60 days. Due to their feeding on decaying plants and insects, earwigs are often called environmental janitors. They also prey upon garden pests like aphids. Their total lifespan is about a year, with adults overwintering in the soil.
Male earwigs have an elaborate courtship with females! They use their cerci to stroke and tap the female. He then presents them to the female for her to nibble on, likely to receive a chemical cue before she decides if he’s the right male for her. Males will also user their cerci to fight each other for females and to hold the female while mating.
Super Mom! - The females display excellent parental care and would be great on any superhero team, providing support and snacks. Every studied species of earwig has exhibited maternal care though the methods may vary between species. One species, the hump earwig (Anechura harmandi), takes this to the extreme. The last motherly act she takes is to feed herself to her young.
Pincers - males and females use their ceric, or pincers, to defend themselves and hold prey. While they will pinch humans if you pick one up, it is unlikely to hurt.
Gross Smells! - some species of earwig will emit a foul-smelling liquid to deter predators. It resembles the scent of a bad battery, kind of acrid.
Earwigs in Culture:
In Star Trek II: Wrath of Khan Chekov and Terrell have an earwig inspired creature, Ceti Eel, placed in their ears by Khan.
In Roald Dahl's book George's Marvellous Medicine, George's Grandma tells him to eat celery that has earwigs and beetles on it. She said “A big fat earwig is very tasty.”
In some regions of Japan earwigs are referred to as Chinpo-Basami or Chinpo-Kiri which translates to “penis cutter.” This is likely due to their presence near old-style toilets.
Boos, Stefan, et al. "Maternal care provides antifungal protection to eggs in the European earwig." Behavioral Ecology 25.4 (2014): 754-761.
“Earwigs.” Extension.umn.edu, extension.umn.edu/nuisance-insects/earwigs.
“Earwigs.” Australian Museum, https://australian.museum/learn/animals/insects/earwigs/
“Earwig.” Wikipedia, 31 Oct. 2020, en.wikipedia.org/wiki/Earwig.
“Earwigs: Identification; Biology; and Control.” Harvard University Environmental Health & Safety Pest Control Office: Fact Sheet, https://www.maine.gov/dacf/php/gotpests/bugs/documents/Earwig-harvard.pdf
Hausheer, Justine E. “Weird and Unbelievable Facts about Earwigs.” Cool Green Science, 13 July 2020, blog.nature.org/2020/07/13/weird-and-unbelievable-facts-about-earwigs/.
Kölliker, Mathias. "Benefits and costs of earwig (Forficula auricularia) family life." Behavioral Ecology and Sociobiology 61 (2007): 1489-1497.
Msrshall, Adrian G. "Interrelationships between Arixenia emu (Dermaptera) and molossid bats and their ectoparasites in Malaysia." Ecological Entomology 2.4 (1977): 285-291.
Mogbo, T. C., and C. E. Akunne. "Ecological survey of earwigs (Hemimerus talpoides) as ectoparasites of wild African giant rat (Cricetomys gambianus) in Awka, Nigeria." Journal of Natural Sciences Research 4.18 (2014): 36-39.
Suzuki, Seizi, Masashi Kitamura, and Kei Matsubayashi. "Matriphagy in the hump earwig, Anechura harmandi (Dermaptera: Forficulidae), increases the survival rates of the offspring." Journal of Ethology 23 (2005): 211-213.
Van Meyel, Sophie, Séverine Devers, and Joël Meunier. "Love them all: mothers provide care to foreign eggs in the European earwig Forficula auricularia." Behavioral Ecology 30.3 (2019): 756-762.