Due to the mild winters of recent years, earwigs have successfully migrated north and established themselves in the yards and gardens of Northwestern Ontario. By far, earwigs seem to be the insect that makes humans cringe the most. When mentioned in conversation, even those that have never seen an earwig have a look of disgust on their face and a comment to match.
But before we are too negative about earwigs, we must review their positive side. Yes, Earwigs do have some redeeming qualities. They clearly walk the line between being a beneficial garden insect or a garden pest. Most people do not realize that earwigs are omnivorous, which means they eat both meat and plants. In the insect world, this means that earwigs also eat other insects, their eggs and larvae. The earwig is a scavenger, roaming the yard and garden for delicacies like aphids, mites, nematodes, slugs and their eggs, other soft bodied insects and decaying plant matter. If none is found then they will seek their food source from live plants, which is when the gardener notices the damage and complains about the destruction they cause.
Earwigs will eat ornamental and vegetable plant leaves and tender roots, particularly dahlias, marigolds, zinnias, sunflowers, grasses, butterfly bush, hollyhocks, lettuce, strawberries, potatoes, roses, bean and beet seedlings, berries, apricots, peaches as well as the silk of sweet corn. Earwigs are also notorious for eating holes in buds and blooms of Clematis while leaving the foliage alone. When serious feeding damage occurs, leaves will have numerous small, irregular holes, giving the plant a ragged appearance. As this type of damage can often be mistaken for the same type of damage caused by other pests such as slugs, it is important to be sure you’ve identified the real culprits by looking for feeding earwigs on your plants after dark.
Earwigs are brown to black glossy flattened insects that measure 1/2 to one inch long. They have a pair of curved pincers or forceps emerging from the tip of the abdomen. They use their pinchers for hunting and securing other insects. Adults may or may not have wings, but they rarely fly. Earwig larvae resemble adults because they develop from egg to adult through gradual metamorphosis, with four to five nymphal instars, or stages, similar to grasshoppers.
During the spring or autumn, females lay 20 to 50 smooth, oval, pearly-white or cream-coloured eggs in the upper two to three inches (5 to 7.6 cm) of soil. They are unusual among insects in that the female fusses over her eggs and nymphs, and uses her pincers to protect them. Most species have one generation a year, but in milder climates, some remain active all year. Both eggs and adults overwinter in the soil or under garden debris, stones, and boards. Adults and the young require moisture to live which is why they are found in damp areas. Earwigs are unable to crawl long distances, but often hitchhike in laundry baskets, cut flowers, luggage, newspapers, lumber, baskets of fruits and vegetables, automobiles, etc.
Usually, the damage to plants, caused by Earwigs is minor, unless their populations are high. As Earwigs hide in cool, moist places during the day and feed at night, good housekeeping practices in the yard and garden can go a long way in reducing populations of Earwigs. Here a few simple tips for prevention:
- Clean up garden debris and organic mulches, especially around foundations, since these moist areas serve as daytime hiding spots for Earwigs.
- Spread dry gravel as mulch next to foundations.
- Earwigs are attracted to lights, so eliminate or reduce lighting around foundations.
- Remove leaf litter, large stones, dead wood, wood piles, and mulches.
- Keep shrubs neatly trimmed to allow for light penetration and air circulation, especially near the base of the shrub.
- Discourage and reduce entry into buildings by caulking and repairing, cracks and crevices, and checking door thresholds, windows and screens for a tight fit.
I hope that this column helps you to better understand the role that earwigs play in the garden. You will have to decide for yourself if you want the earwigs to remain in your garden to help control the population of other pests, or get rid of them. Stay tuned for a future column that provide a number of solutions that will help you to control earwig populations.
