Sunday, April 29, 2007

Common European Earwig

I am an amateur attempting to identify every (tolerably sized - see here) living thing in my garden.

Beneath a pile of wood (at (1.8,2.0) - see here), I found the earwig in photo 1 (click on it to enlarge). Having almost no knowledge of insects, I spent some time browsing books on beetles in an attempt to pin down the Latin species name for my earwig. It turned out this was entirely the wrong approach however, since (as I discovered) earwigs are not in fact beetles at all (in the strict scientific sense of being members of the the order Coleoptera). Rather they are members of the insect order Dermaptera (from the Greek Dermatos: skin; Pteron: wing - "leathery wings")

This led me into something of a digression seeking to get to grips the whole business of orders, genera etc. - words I've seen and read many times but have always been slightly hazy about. You'll want to skip this paragraph if you're not. There are countless places you can turn to get a detailed understanding of this sort of thing (the highly worthy Tree of Life project for example). In my case, I found Insects (G. C. McGavin, Dorin Kindersley handbooks) served me well. In brief: part of the Kingdom Animalia is the Phylum Arthropoda (= all those animals having in common certain gross features -an exoskelton, jointed legs, jointed bodies). The Arthopoda are sub-divided into the Sub-Phyla the mandipulata and chelicerata partly on the basis of whether they have chewing- or pincerlike- mouthparts (spiders, with their pincer-like chelicera mouthparts - see my previous blog posting - fall in the latter). The sub-Phylum mandipulata breaks into 3 Super Classes (the Hexapoda = 6-legs; Crustacea=gills; Myriapodia= millepedes etc.). The super-class Hexapoda next sub-divides into the classes Insecta (wings) and non-Insecta (non-winged springtails etc.). Next, the class Insecta contains 29 orders - examples include the Hymenoptera (ants,bees,waps), Coleoptera (beetles), Dermaptera (earwigs etc.). Below this you get Families, for example the ant family, the Formicidae. The Formicidae are then broken into various ant Genera based on common features (e.g. all those ant species where the waist comprises, say, 2 body segments). Finally, you get the individual species. There are so many insects that as an amatuer you are often doing well if you can get an identification down to the family !

From the Tree of Life project I learn that the order dermaptera (earwigs) comprises 1800 species. The dermaptera seem to those insects that posses two pairs of wings, where the forewings are modified into leathery, stubby tegmina, together with the characteristic unsegmented pincers (cerci) at the end of the body. Gordon's Earwig Page has some more information and a handy set of earwig links.

Much the most comprehensive earwig site I've found is that of Fabian Haas which includes numerous wonderful close up photo's of different species. From the photo on this site I'm almost certain my earwig is The Common or European Earwig (Forficula auricularia).

Despite the fearsome-looking cerci (pincers), it seems the earwig is a gentle creature. It's cerci are quite incapable of having any impact on a person's skin. Earwigs mostly scavenge on leaves and rotting matter and are fairly unusual in the insect world in being doting parents: A female earwig apparently remains with the eggs she lays, carefully cleaning and rearranging them until they hatch. I shall look on my garden's gentle earwigs with a new fondness.

3 comments:

Laura said...

I remember being fascinated with earwigs as a kid. I attempted to make a treehouse out of corrugated cardboard with minimal success but it became a fantastic home for these creatures.

You can sex an earwig by the shape of the pincers, the female's being straighter than the curvy male counterparts.

Henry Walloon said...

Thankyou Laura and nice to see you here again.

You live and learn!

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