European Earwig

family: forficulidae
species: forficula auricularia
common names: european earwig
antennae characters: moniliform
specialties: female guards young and nest
hosts: cornsilks, melon flowers, young seedlings, strawberry, strawberries
natural enemies: shoes
cultural control methods: rolled newspaper
physical control methods: tidy up, remove leaflitter
pesticides used: poison bait, sevin, carbaryl
notes:

THE FOLLOWING (UNTIL OTHERWISE NOTED) IS FROM: GERBER, H.S. 1983.
MAJOR INSECT AND ALLIED PESTS OF VEGETABLES IN BRITISH COLUMBIA.
MINISTRY OF AGRICULTURE AND FOOD.

European Earwig

Forficula auricularia Linneus

Earwigs can overwinter only under moderate climatic conditions. They occur generally in southern coastal areas and sporadically in the Interior. Earwigs hide in cracks and crevices during the day and because of this habit are readily transported from one place to another.

Vegetables attacked:

Most vegetables, corn, lettuce

Injury:

Feeding damages all plant parts, including seedlings, foliage, flowers, corn silk and corn kernels. Besides causing feeding damage, ear wigs dirty vegetables, making them unmarketable. Live earwigs may remain in harvested crops, especially corn and lettuce, thus making such produce unmarketable.

Insect:

The adult earwig is about 1.5 cm long and red-brown. It has short, squared-off wing covers and curved pincers at the rear of the body. Immature stages are similar in appearance to the adult, but smaller.

Life History:

There is one generation a year; adults overwinter. In the spring, eggs are laid in nests in the soil; some females lay a second batch of eggs. Adults care for the young nymphs, which leave the nest when about 6 mm long. Nymphs reach the adult stage in about 70 days. Earwigs are most active at night and hide in foliage, cracks, or debris during the day. Control: A parasitic fly has been released in some areas of British Columbia but has been partially effective only in the southern coastal region. Apply insecticides to the base of plants early in the season. Some earwigs may be trapped by laying out corrugated cardboard in which they will hide. This cardboard must be gathered up as often as convenient and burned.

Name: Gilkeson, Linda A. Title: Integrated Pest Management Coordinator
Company: Ministry of Water, Land and Air Protection

Reference Text:

Earwigs are a nuisance when they get into the house, but outdoors they are an important predator of aphids and other pests in orchards. They also chew on flower petals, corn silks and enlarge puncture wounds in ripe fruit. Prevent them from entering the house with good screens and sealed cracks; after cutting flowers or picking vegetables, give the produce a good shake outdoors to dislodge earwigs before you bring it indoors. If you really must kill earwigs, trap them in tightly rolled up lengths of corrugated cardboard or newspaper or in half-meter lengths of old garden hose. Lay the traps along the baseboards or inside the house foundation where the earwigs seem to be entering. The traps are attractive because earwigs like to crawl into tight crevices. You can kill the earwigs hiding in the traps by knocking them into a bucket of soapy water or by disposing of the entire trap with the earwigs.

Notes on Behaviour of a European Earwig (Forficula auricularia)

Everyone knows earwigs. Most people don't have much use for them. Some are definite pests of small seedlings, but overall they tend not to be pests of crops or plants in general. In fact some species are predacious and play a role in controlling mites and aphids. I would say that it is the fact they just get into every nook and cranny that makes them irritating. It is probably this characteristic that initiated the belief that the earwig would climb into people's ears.

In July of 1994 I observed another little known defensive behaviour in the earwig. A mature earwig was observed carrying an adult house spider (Acharanea tepidariorum). The earwig was using its cerci and had caught the spider between the abdomen and its cephalothorax. As the spiders legs were facing upwards, it was unable to gain any purchase or grip and was thus defenseless.

I am unsure of the events that lead to this observation. I can only assume that the earwig had blundered into the spiders web. The spider had reacted by attacking the earwig. In this case the spider would have come down the web and then attempted to subdue the earwig by throwing silk at it to restrict the preys movement. The earwig in response would have lifted its abdomen over its head and closed its cerci around the spider. In the struggle that followed, the spider must have lost its grip allowing the earwig to escape. The result was the trapped spider.

I do not know how long the earwig would hold the spider in this manner, but it was certainly long enough for the spider to give up its attempt at prey capture. Although I had been pinched by earwigs, I had never seen or heard of these cerci being of any real use. The observation was therefore a surprise. In all references that I have subsequently looked up, I have only come across one other comment on a similar behaviour. Swan & Papp (1972) report the cerci were used against ants that attacked them. In this case the spider was definitely unable to protect itself when it was observed.

It would be interesting to note just how well developed this technique is in the various species of earwigs. It is behaviour such as this that could account for the earwigs tremendous success in establishing itself. I would be interested in hearing from anyone that has seen similar occurrences.

Reference: Swan, L.A. and C.S. Papp, 1972. The Common Insects of North America.

Tom Mason Curator of Invertebrates, Metro Toronto Zoo