Skin Wings — Earwig wing folding

The wing folding of the common earwig (Forficulidae).

Just a quick set of pictures I threw together while I was practicing my wing spreading techniques.  Earwigs are tricky because their hind wings are so delicate, as well as compactly folded.  In earwigs the hind wings are hidden under the short tough forewings (tegmina) and may be folded up to 40 times.  Earwigs can actually use their pincers to help them fold up their wings like insect origami  You can see some of the fan folding in the third picture.  For some reason the wings also seemed to want to twist upside down on me.

The order name Dermaptera means “skin wings” and refers to the leathery texture of the forewings.  I was surprised to learn earwigs had wings when I started studying entomology, because the common species we have locally is secondarily wingless in the adult form.

The Common Earwig

Male earwig in leaf litter (San Diego, California).

Here’s some more shots of the earwigs I came across flipping stones during the ESA conference in San Diego.  We mostly only see the small, wingless Anisolabididae in my area so I was unreasonably impressed and excited by these common or european earwigs (family Forficulidae).  Nonetheless, these are interesting little insects to take a closer look at.  Aside from the females guarding eggs and nymphs, it was also interesting to observe the range in sizes of the cerci, which are adapted into pincers in earwigs.  Starting with the short straight pincers of the female earwigs, these cerci ranged from similarly sized but curvier pincers in the males to large curved scimitars nearly twice as long.

Male and female common earwigs (Forficulidae).

These earwigs are fairly easy to handle, being generally unaggressive towards humans.  When threatened, they may attempt to pinch with their cerci, but rarely have enough of a grip to do any damage.  However, I did manage to acquire a war wound while playing with these fellows.  One of the males caught my finger in a particularly vicious pinch and actually drew blood with his cerci.  Since my brain has been warped by entomology I reacted by being impressed and interested.  I went around showing my finger to my fellow entomologists and asking if they knew earwigs could do that (they were universally surprised).

Of course, I took the moral of the story not to be “don’t handle earwigs” but more of a “be careful with sharp objects.”  Even peaceful cicadas have been known to get in a chance stab with their proboscises.  On the whole I’ve found it’s much more useful (and entertaining) to know where the sharp bits are and how to avoid them.

A male earwig held in hand.

New Year’s Babies — Maternal care in earwigs

An earwig mother guards her clutch of eggs (San Diego, California).

 When most people think of earwigs–if they think of them at all–they think of them as creepy little bugs that turn up in leaf litter, along the foundations of houses, or occasionally in bathrooms or basements.  Few people realize that these insects can also be excellent mothers.  Female earwigs in the family Forficulidae (latin for ‘earwig’, originating from the word for scissors) carefully tend their clutch of eggs, guarding and caring for the youngsters after hatching. 

In the extreme example of the hump earwig, these mothers make the ultimate sacrifice, allowing their children to kill and eat them at the end of their care.  This phenomenon is giving the charming name of ‘matriphagy’ and increases the offsprings’ chance of survival.  A mother’s love?

A mother earwig (Forficulidae) watches over her eggs.