If you have noticed any odd damage to your flowers or garden plants this summer, you may have been victim to earwig feeding. Earwigs are odd-looking insects that feed on a wide variety of food, but in the summer, they can become a cryptic garden pest as well. Other times of the year, earwigs can be encountered in piles of firewood, in mulch beds, and even in the home. Wherever they are found, they often startle people and their name hints at some of their creepy past. Luckily, there are several ways to get a handle on these entomological oddities.
Earwig Basics
The name “earwig” refers to a small order of insects that have the scientific name of “Dermaptera,” which translates to “skin wing.” Earwigs tend to be flattened, dark in color, and are most famous for their cerci –the pincher-like organs at the rear of their body. Male earwigs have curved cerci, whereas females have straighter cerci.
In Kentucky, people mostly encounter the European earwig. This species is about half an inch long and has a dark red-brown color. Like other earwigs, it has short leathery covers that protect the folded-up membranous wings. These softer wings are folded-up, origami style, and when unfurled they are vaguely ear-shaped. European earwigs are not strong fliers, though.
Earwigs are omnivores and scavengers. The European earwig will feed on plant leaves, flowers, and fruits, as well as preying upon aphids and consuming rotting plant and animal material. They like to hide in tight, moist areas and go through incomplete metamorphosis. Females overwinter in an underground home that she builds in the autumn. While there, she will lay a clutch of eggs that she tends to through the cold months until they hatch in the spring. They display maternal behaviors, tending to the young until they mature.
Earwig Myths
Earwigs are known to have superstition and folklore that surrounds them. The name earwig is thought to derive from an Old English word “earwicg” that means “ear creature” or “ear beetle.” Other European nations also have a name that refers to the earwig as something that wants to invade the human ear. Even more sinister, some have believed that this insect deliberately wants to bore through the ear canal and try to get to the brain. It’s unknown how this superstition came to be; there have been instances where earwigs have been found in human ears, but they don’t appear to seek them out for shelter, nor have they ever actually been recorded to consume brains. Sorry, sci-fi and horror fans.
Real World Earwig Problems
In reality, earwigs are more of a problem when in the garden, rather than digging through your earwax. There are always some earwigs around; they can be in tree hollows, under paving stones, hiding under potted plants, and in wood piles. In these situations, they will feed on dead insects, prey on some small species, and scavenge food from all over. Unfortunately, they will also feed on plants like cabbage, beets, potatoes, and cucumbers. They can also feed on ornamental plants like roses, marigolds, and dahlias.
Earwigs will chew through leaves and blooms, leaving behind irregularly shaped holes. This can superficially resemble slug, snail, or caterpillar damage. Snails and slugs would also leave behind a shimmery trail or slime after they have fed, and caterpillars also tend to leave behind tell-tale frass or webbing (though not always). Earwigs come, eat, and leave without leaving behind much evidence. Unfortunately, this is a case of proving a problem through negative data; you have to look for the absence of these other signs to try and confirm an earwig problem. If earwigs are suspected, come back to the damaged plant at night to try and catch them in the act to confirm the problem.
Management
Deterrence
There are ways to deter earwigs from making holes in all your plants.
- Opening up an ornamental area to increase air flow and sunlight infiltration can scare away earwig populations.
- Using a thinner layer of mulch in gardens and flower beds reduces harborage for them.
- Garden sanitation to remove old plant debris may also remove hiding spots.
Traps
Some gardeners use to confirm the presence of earwigs and to suppress them.
- Traps can be as simple as loose newspapers or cardboard laid in the garden. Earwigs will hide in/under these during the day and then the whole paper or cardboard can be picked up and disposed of.
- Alternatively, using a sour cream container or tuna can, a baited trap can be constructed. In the evening, place the cans in the ground near damaged plants and fill the bottom with fish oil or vegetable oil with bacon grease to lure earwigs in. Some may drown but the traps can also be emptied into soapy water to kill any surviving earwigs.
Chemical Management
Finally,
- Applications of residual insecticides can kill earwigs as they damage plants. Bifenthrin, cyhalothrin, permethrin, and deltamethrin are all possible choices.
- Baits for slugs that contain spinosad can also be considered for earwig control and would offer less hazard to non-target organisms.
By Jonathan L. Larson, Entomology Extension Specialist
Kentucky Pest News 