Earwigs (Forficula spp.) are crawling insects with dark red-brown bodies and two pincers on the rear end. Looking scary but harmless to humans, earwigs tend to hide in dark, moist locations and then come out at night to feed on tender shoots and flowers on plants. The presence of earwigs in your vegetable garden means overly moist conditions, the result of over-watering, too much rain, too closely spaced plants or too much mulch or other moisture-retaining items on the soil surface.
Create Habitat Unfavorable for Earwigs
Some earwigs in your vegetable garden are good, since they will attack and eat unwanted insect pests like aphids, mites, fleas and their eggs. When soil remains overly wet and shaded and there is an abundance of tender, tasty young plant shoots, leaves and flowers to feast upon, the numbers of earwigs tends to get out of hand, to the detriment of the garden. Good garden maintenance can greatly cut down on earwig numbers, as advised by the University of Wisconsin Cooperative Extension.
Cultivate the soil with a hoe, which helps destroy their burrowing tunnels and expose their eggs to drying air and sunlight. Remove thick mulches in-between vegetable crop rows so earwigs have little place to hide and survive during the day. Also thin out plants or create more air-flow around vegetable plants in rows and the row spacings to help dry out the soil and plants that reduce both the fungal diseases and overly moist conditions earwigs prosper in.
Promote Habitat for Natural Predators
Just like earwigs feed on smaller insects, there are critters that love to eat earwigs. In any healthy garden environment, these predators and prey live in good balance. Avoiding the use of chemical pesticides reduces chances of killing off the good insects in your garden while they attack the bad ones. Also planting plants or crops that tend to favor the reproduction of the earwig's predators is a good idea. Two parasitic flies feast on earwigs and can be attracted to your vegetable garden if these plants are nearby: anise, tickseed, cosmos, dill, fennel, golden marguerite, painted daisy or tansy. Moreover, Phil the Gardener online notes that lizards and toads eat earwigs, too, so don't scoot them out of the garden next time.
While you are employing better vegetable gardening techniques and promoting habitat for predator insects that eat earwigs, you can lure earwigs into easily made traps overnight and then drown them in a bucket of soapy water in the morning. The University of Wisconsin Cooperative Extension advises you lure and trap earwigs in rolled up, dampened newspapers laid on the soil in-between crop rows or in old tuna fish cans baited with fish oil or vegetable oil. Place traps near the problem areas and check them each morning.
Phil the Gardener suggests a shallow tray of oatmeal laced with boric acid to kill the pests, or laying jars on their sides with a shallow pool of beer inside. The earwigs will crawl into the jars overnight and you can shake them into the soapy water to kill them in the morning. Remember, earwigs shy away from light, so clean traps at dawn before earwigs scatter to hide in even darker locations during the daytime.