Most North American gardeners see earwigs (Forficula auricularia) as an enemy. But in fact, they are more likely to be friends, at least as long as they’re present in reasonable numbers.
The main role of earwigs is to decompose organic matter: leaves, garden waste, etc. What’s not to like about that? Moreover, they are also predators on many small soft-bodied creatures like aphids, mites, scale insects, slugs, and other pests. So, there are at least 2 points in their favor.
When They are Bad…
The catch is that they are also omnivorous and have a wide range of favorites: when there is nothing organic to break down and no insects to eat, they turn to plants, including garden plants such as dahlia, rose, clematis, zinnia, coneflower and sunflower blooms, lettuce, beet and celery leaves, and also seedlings, including young bean plants. They’ll even munch on the silk of corn leading to irregular grain production.
Furthermore, humans seem to have a natural disdain for earwigs. Even though they are harmless to people (the idea that they can take up residence in our ears is a long-standing myth), we find their appearance repulsive, particularly because of their pincers, even if they are not sturdy enough to hurt us.
Even worse for most people is that earwigs tend to migrate into our homes. They don’t do it on purpose, but since they like to hide in tight, dark places during the day, they find the cracks in our homes, especially around doors and windows, really great spots in which to rest. Then they accidentally work they way indoors and can’t find a way out. They also come indoors on garments brought in from the clothesline (yes, earwigs can fly).
In spite of the above, earwigs can’t live in our homes, cause no damage while they are there, and eventually die if they can’t find an exit. Still, they can certainly give you a good scare when one falls onto the counter as you open a cabinet door.
Meanwhile, Back in Europe…
Earwig are not native to North America. They were introduced accidentally into the ports of North America from Europe in the early 20th century and have been slowly extending their range ever since.
In Europe, the attitude towards earwigs is very different to the North American one. Europeans have long known that earwigs are beneficial and, rather than trying to reduce their numbers, gardeners there set up earwig houses in their gardens to attract them, especially in orchards where their effectiveness in controlling fruit predators is well-known .
Treatments Give No Worthwhile Results
When your neighborhood is going through an earwig outbreak, there are dozens of techniques you can use to try and control them – traps made of sardine cans, insecticide sprays, a broom left standing overnight, a rolled up newspaper left on the ground, etc. – and all “work” in the sense that they do allow you to kill quite a number of earwigs. But the sad reality is that when a major outbreak is going on, killing earwigs is essentially a waste of time. You see, the population pressure is enormous at that time: for each earwig you kill, another will quickly take its place.
I’m not saying you shouldn’t try: it can be enormously satisfying for humans to kill their insect enemies, even if, in the end, it makes absolutely no impact on the overall population. At least you come away with the impression you have somehow protected your home from a nasty invader. A sort of insect placebo, if you like.
After the Outbreak is Over
The true secret of effective earwig control is… to be patient: Mother Nature will eventually step in and give you a hand. Remember that earwigs are only truly harmful when they are present in large numbers. When they arrive in a new region, there is usually a population explosion and you see earwigs everywhere (try opening your outdoor barbecue and count the number of earwigs that fall out!). However, after 2 or 3 years of earwig horror, the population drops sharply, then stabilizes. This appears to be mostly due to fungal diseases, parasitic nematodes and a parasitoid fly introduced from Europe. Once the population drops, earwigs become beneficial insects again and no longer cause gardeners problems.
While an outbreak is going on, the best thing to do is to plug any openings in your home (that will also help prevent other unwanted insects, such as ants, from wandering in) and avoid planting their favorite plants (dahlias, lettuce, etc.: see above for others) for a few years. Bring all clothes in from the clothesline before dark (earwigs only fly at night and won’t find their way into your garments during the day) and don’t bring potted plants indoors without immersing their pots in soapy water.
Patience! Earwig invasions don’t last forever and you will soon be able to garden normally again!