There are several species of earwigs. Their food habits are variable, eating anything from decaying plant debris to living plants. Some species are predaceous on other insects. The “European earwig” is found throughout North America and is the species that is the most troublesome to gardeners. The young and adults are nocturnal, moving about and feeding at night. Acceptable food is all kinds of flowers, ornamentals, fruit, and fruit trees, vegetables, grains, and grasses. They will also enter houses and can become a major nuisance. On the Central Coast, I have seen earwigs cause major damage to dahlias, pansies, roses, and other flowers. They will eat vegetable seedlings of all types. They also will eat apricots, peaches, plums, apples, and other fruit as well as the leaves of the tree.
An interesting side note is that the female earwig makes a nest for her eggs and then tends the eggs and cares for her young for a short time after the eggs hatch.
Earwig control or earwig management can be done in several ways. The first consideration is sanitation. Earwigs hide in damp, dark places during the day. Therefore, cleaning up plant debris to destroy hiding places is useful. Also since most of these insects hide within an inch of the soil surface, a frequent, light cultivation (disturbing the surface soil) will help destroy egg masses and expose the young and make the cultivated area an unfavorable habitat. Using drip irrigation is also useful as it reduces surface soil moisture, keeps plants dry, thus making a less favorable earwig habitat.
Earwigs like to hide in dark places. Make an earwig trap by using a newspaper. Fold several (2-3) pages of the paper into an accordion fan. Take another page and roll the accordioned pages inside. Secure the roll with rubber bands or tape. Now you have a 2-3 inch diameter “log” with many folds into which earwigs can crawl to hide during the day. Place these “paper log traps” around the garden where you have earwig activity. Place them in the evening, so that earwigs can take advantage of these new hiding places the next morning. About mid-morning collect the traps, put them in a plastic bag (the one the newspaper came in is good), seal the opening and place the bag in the trash can. Place new traps in the garden. This process done over several weeks and then repeated monthly or so should keep the earwig population at tolerable levels.
Finally, there are poison baits that can be spread in the garden to kill earwigs. These are compounds specially formulated usually with fish oil to be attractive, as a food, to earwigs. The bait, pellets or granules should be scattered on the soil where earwigs are active. The baits need to be periodically reapplied to keep the earwig population in check. Always read and follow the package label directions for best results.