Inner Beauty: the surprising world of Dermaptera
For this week’s blog post, I decided to highlight an entire order which I am fond of, albeit a rather small one. Dermaptera, which, as of 2012, contains only 2,000 species. That’s a stark contrast to the hundreds of thousands of species in the “big four”! While small, Dermaptera is not unfamiliar- they are better known as earwigs.
If you were to ask a past version of me about my feelings on earwigs, my answer would have been quite negative. While I’ve always liked most bugs, earwigs’ slithering movements and menacing-looking cerci used to repulse me. Then, a couple of years ago, I came across an extraordinary image on the internet.
Earwigs with wings folded and opened. Hans Pohl on Twitter, https://x.com/hans_pohl/status/1198909468412710913
Inside their flat little bodies, earwigs were concealing a most remarkable set of wings, shimmering with rainbow iridescence and almost shaped like seashells.
Suddenly, I couldn’t get enough. I googled “earwig wings” and was shocked to find that this natural origami is so complex that mechanical engineers are studying it for use in robotics and other technology.
3D-printed recreation of an earwig wing. Dr. Jakob Faber, ETH Zürich https://arstechnica.com/science/2018/03/earwigs-wing-inspires-compact-designs-that-fold-themselves/
(To see how earwig wings fold, see this gif, which was not loading correctly on the Blogger page: https://www.purdue.edu/uns/images/2018/wing-unfolding.gif )
Earwig wings break all the rules of origami theory (yes, that’s a thing). Unlike paper, which cannot stretch very far without tearing, earwig wings have an elastic quality thanks to the protein resilin. This allows the folds of the wing to act like springs, storing energy as they stretch before snapping into place. Because of this unusual property, the origami structure is strong and stable in both an open and folded position.
This experience caused me to wonder: what other secrets could earwigs be hiding? I began educating myself. Firstly, it was important to clear up some misinformation. While earwigs do use their characteristically large “pincers” in self-defense, they are not strong enough to injure humans. Rather, the cerci act as multipurpose tools used to grasp prey, grasp each other during copulation, and put away their magnificent wings. Cerci are also a useful field mark to instantly sex an earwig- males have large, curved cerci, while females have smaller, straight ones.
After this, I quickly learned about another endearing aspect of earwigs: they are wonderful mothers.
Mother earwig guarding her eggs and nymphs. Tom Oates, 2010 https://commons.wikimedia.org/wiki/File:Nesting_Earwig_Chester_UK_1.jpg https://commons.wikimedia.org/wiki/File:Nesting_Earwig_Chester_UK_2.jpg
Most insects do not provide much maternal care beyond providing their eggs with a suitable food source. Earwigs, however, display some of the most elaborate behavior outside of the eusocial hymenopterans. First chasing away the male, the female uses her mouthparts to dig a chamberin the soil, often under an object such as a large stone. After laying her eggs, she will not even leave this nest to forage for food. During this time she will frequently groom the eggs to prevent fungal growth and apply chemical protection. Female earwigs defend their nests aggressively, using their strong cerci and unpalatable chemical sprays if a predator intrudes. They may even go so far as to chase off other female earwigs and adopt their eggs!
Earwigs are hemimetabolous, so their eggs hatch into nymphs with a similar appearance to adults. In some species the female continues to stay with her young after hatching, continuing guarding and grooming behaviors. She may also bring them food or, in a very small number of species, sacrifice her own life for food in matriphagy.
In general, earwigs are omnivores or scavengers, with a few species that hunt other insects. This can be either harmful or helpful to humans, as earwigs can become pests of crops but also act as biological control of other pests such as aphids. The most extreme modifications of lifestyle and body occur in the families Arixeniidae and Hemimeridae, which are ectoparasites of bats and giant rats, respectively. Hemimerids in particular have stubby, clawed legs for clinging to fur, strikingly similar to those of lice.
Hemimerus sp. on fur. Neubert, D., Beutel, R., & Wipfler, B., 2015 https://commons.wikimedia.org/wiki/File:Hemimerus_sp._on_fur.jpg
I am out of time and word count now, but I hope I have succeeded in inspiring you with a newfound respect for this fascinating and misunderstood group! Now that I know how to pin insects, I would love to find an earwig and see their marvelous wings for myself. Perhaps, with your help, we can find some and add another order to our collections!
References:
Zhi-Qiang Zhang, “Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness”, Zootaxa, 2011
https://mapress.com/zootaxa/2011/f/zt03148p103.pdf
Kayla Wiles, Purdue University, “Origami folds of insect wing can help improve machine functions”, 2018
Marshall Cavendish, International Wildlife Encyclopedia, Third Edition, Volume 6, 2002, pp 738-740
https://books.google.com/books?id=0gsPc5lk7_UC&q=earwig#v=onepage&q&f=false
Joël Meunier, “The Biology and Social Life of Earwigs (Dermaptera)”, Annual Review of Entomology, 2024
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