WSU TIMELY TOPICS By Island County Extension Agent, Donald B. Meehan
THE REMARKABLE EARWIG
One of the more remarkable insects that can be a pest in gardens in western Washington is the European Earwig. As its name implies, it was introduced from Europe early in this century and seems to have found the conditions in our region particularly suitable. It is now a naturalized citizen. Although in most cases, earwigs are considered benign plant pests in that the damage they do is usually not very extensive, or perhaps not diagnosed, sometimes the damage in gardens is fairly serious. Seedling vegetables can be completely destroyed by earwigs, as can the seedlings of many other plants. This was brought very close to home when a pot of seedling Carpenteria californica, the bush anemone, was worked over quite thoroughly by a group of earwigs in my garden. I saw the beasts actually chewing away on these defenseless little plants one night recently with the aid of a flashlight. Like a number of other pests, most of their damaging handiwork seems to be done at night; during the day they are hiders-under-things.
Commonly the foliage of beans, potatoes, beets, cabbage, cauliflower, peas, dahlias, zinnias, sweet williams and even figs is prime fare for an earwig's overnight meals. Many flowers are injured too, when petals and other parts are chewed on. The typical sort of injury encountered is numerous, smallish, irregular holes in leaves and petals. Berry bushes and even tree fruit are host to earwigs. In fact, it's not uncommon to find them inside of ripe apples, plums and peaches.
For those of you who don't know what an earwig looks like, it resembles a narrow, wingless, or short-winged beetle with pair of forceps at the rear of the body. Often when confronted or threatened, these forceps are raised as if the insect was going to use them to pinch; however, in the numerous times I've handled them, I've never really been hurt by these pincers. It's not very likely that they could cause any sort of wound. Incidentally, although they were originally named earwigs because it was thought they crawled into the ears of sleeping persons to do damage, this has since been proved to be without foundation. Earwigs can also be found in and about homes, lurking around in kitchens, closets, and garbage cans. In its search for food, it can get into just about anything, and often does.
Unlike most insects, the female earwig actually guards her eggs and watches over the young during the first stages of their life. It's the young ones that seem to do the most damage to young seedlings while the adults work on flowers of all sorts. They do seem especially fond of eating the bases of rose and dahlia petals. Like a lot of organisms in nature, the earwig has a good side too. They are beneficial in that they feed on decaying organic matter, and they also eat the larvae of other insects as well as slow-moving animals like slugs and snails. I wouldn't however, depend on them to make any dent in western Washington's slug population.
Earwigs are quite frequently found under containered plants, especially outdoors. Obviously, they hide under the pots during the day and emerge at night, often to climb up on the plants in the pots to feed on them. If obvious damage is being done by them, either in this sort of situation or some other garden setting, then control may be necessary. However, before embarking on a control program, because of their beneficial side, it would be prudent, I think, to be absolutely sure you've got a problem and the earwigs are at fault.
Current recommendation for earwig control in garden settings is to use a 5% Sevin dust on soil surfaces that they inhabit. This could certainly be applied underneath potted plants outdoors and should give good control. To keep them out of fruit trees, sprays of 50% Sevin wettable powder is recommended around the bases of trees. If you decide to use Sevin, be especially careful not to apply it in the vicinity of bee activity. This stuff is deadly to bees and before using it, absolutely read and follow the label directions explicitly. Earwigs in the home can be controlled mechanically by vacuuming them up or sweeping them back outside. There are also numerous insecticides registered for use in and around the home to keep them out and to get rid of them in the house if and when they do get in.
My thanks to George Pinyuh, King County WSU-Extension Agent for the use of this material. For more information about other yard and garden pests contact my office
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