Written by Raymond Nakamura
Once upon a time (before the Internet), Raymond earned his doctorate studying the hydrodynamics of sand dollars. Nowadays he rents his brain at raymondsbrain.com for writing, cartooning, and thinking, when he is not washing the dishes, walking the dog, or helping his daughter with homework. Follow him on Twitter @raymondsbrain.


Earwigs can be a surprise in some fruits

Created date

Monday, September 24, 2018 - 12:00am

Ever Wonder About Earwigs?

One summer day, I bit into what I thought was a nice nectarine. But inside, the pit was split with two earwigs wiggling in there. I squashed them before my curiosity allowed me to wonder what species they were and what they were doing there. So I am writing this post to make up for my lack of compassion.

Species

The nectarine was from BC and all earwigs in BC are introduced from other places. The ones I saw were about 1.5 to 2 cm long, and I think they were probably Forficula auricularia, the European earwig accidentally introduced from Europe and now widespread. Over a thousand species of earwigs are known, most of them tropical. They occur on every continent except Antarctica. The largest known earwig (>8 cm long!) occurred on St. Helena, the small island in the Atlantic where Napoleon was exiled. The earwig is now considered extinct, a victim of invasive species and habitat loss, among other things.

Pincers

Earwigs are easy to identify by their intimidating rear pincers. More technically, these are called cerci, not to be confused with the character (spelled differently) in Game of Thrones. These extensions can be used for defense and to help manipulate prey, but are not strong enough to harm people. They tend to be more curved in males, which may use them in mating. But they are NOT for eating your brain, like the creature in the Star Trek Wrath of Khan movie. Its name is evocative of some ghastly behaviour, but the wig comes from an old word for insect. Ear may refer to their ear-shaped hind wings that fold up in an elaborate, origami kind of way, that has inspired some robotic designs. Their forewings are short rectangular veinless leathery flaps and they don’t usually fly.

Menu

Although they don’t eat brains, they are omnivores that prefer to dine at night. They prefer soft foods, from soft-bodied insects like aphids, the eggs of insects or slugs to decaying vegetation to flower petals and soft plant parts, which can include fruits like nectarines. They are not, however, responsible for split pits, they just take advantage of them. The split pit tends to occur if the fruit grows too quickly.

Behaviour

Earwigs demonstrate thigmotaxis a “predilection for pressure” and during the day, they like to squeeze into tight spaces, such as a split pit. Then they can feed on the flesh near the pits. Rolled up corrugated cardboard at the base of an infested tree can provide an irresistible refuge for earwigs, which can then be removed. Since they don’t fly, they don’t tend to spread that quickly. Plastic wrap with adhesive the outside, wrapped around the trunk of the tree can keep them from exploring the canopy.

When I saw them, in my ignorant panic, I failed to determine whether or not they were adults and whether they were of the same gender. If you come across them, it might be interesting to find out those things. I hope I don’t come across half an earwig in a snack any time soon, but I did enjoy wondering about them.

Still wondering about insects? Learn about the deadliest insect in the world, or discover if cinnamon can act as as a pesticide.

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