Earwigs belong to their own order of insects, called Dermaptera, the most common of which is Forficula auricula. A nocturnal insect, earwigs prefer to hide in damp, dark areas during the day. They are omnivorous, eating many different types of plants and insects. Earwigs are a huge garden pest and do quite a bit of damage to both flowers and food crops alike.
There are a number of pesticides for outdoor earwig control. Dursban and Sevin are for outdoor use only, while Baygon can be used both inside and out. You can also use any commercial product that contains diazinon, malathion, pyrethrin or other products labelled effective against earwigs. Spray late in the afternoon so that the pesticide will be fresh when the earwigs become active at dusk.
Granules and Powders
Granules and powders containing chlorpyrifos (Dursban), malathion, carbaryl (Sevin), diazinon (Ortho), and cyfluthrin (Optem, Tempo) are effective against earwigs and last longer than sprays. Use these under leaves and in dark, damp places in the garden where earwigs congregate. You can also place the powders and granules in a line around the garden forming a barrier.
Metaldehyde bait is reasonably effective against earwigs, but is poisonous. There is currently no metaldehyde bait considered safe for vegetable gardens; however, bait can be placed outside the perimeter of the garden to eliminate any earwigs living in the vicinity. According to the Ohio State University Extension Office, bait is not as effective as sprays, powders or granules because it takes too long for the bait to control the problem.
Gardeners who do not want to use strong chemicals should consider M-Pede, an organic insecticidal soap. It works by penetrating the earwigs' cuticle and destroying the cell membranes, resulting in death.
Another option is diatomaceous earth. This is a powder made from the fossilized remains of diatoms, a type of algae. It works two ways; first, it gets caught in the insects jointed exoskeletons, cutting them and inhibiting movement. Next, it penetrates their bodies, releasing fluids they need to live.
You can also use boric acid. Sprinkled in places the earwigs crawl though, it sticks to their bodies. When they clean themselves they ingest it. The boric acid works on the nervous system, paralyzing and killing the earwig. Because it stays on the body until the earwig consumes it, some of it will get back to the nest and may kill the entire colony.