Ministry of Agriculture
Grape Insect and Mite Pests
European Earwig
(Forficula auricularia L.)
- Identification
- Life Cycle and Damage
- Monitoring and Spray Thresholds
- Biological Control
- Cultural Control
- Chemical Control
Prepared by D. Thomas Lowery, Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, Summerland.
The European earwig is both a beneficial insect and a pest of table grapes. All stages feed on small, soft-bodied insects such as small leafhopper nymphs and will scrape leafhopper eggs off of leaves. In fall they feed to some extent on damaged grapes and their presence in table grapes is not appreciated by some consumers. On grapes produced for wine, they should be considered important generalist predators.
Identification
Adult earwigs (Order Dermaptera) are dark brown, about 1.5 cm long, with a pair of forcep-like appendages (cerci) at the rear of their elongate bodies. The anal forceps of females are long and straight, while those of males are curved. Earwigs seldom fly and the membranous hind wings usually remain folded up under the short leathery forewings, exposing the abdomen. The four nymphal stages resemble the adults except that they are smaller and wingless. Earwigs are largely nocturnal and hide during the day, often in large aggregations, in cracks and crevices, or under bark. When disturbed they move quickly.
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European earwig |
Life Cycle and Damage
Adults overwinter in the ground in earthen cells. Clutches of eggs laid in cells in the top 5 cm of soil in the fall and spring are opened by females in spring to release the young nymphs. Adults are semi-social and tend their young for a period of time after birth; nymphs later disperse to secure locations under rocks, in crevices, or under bark. Adults develop by midsummer and there is only a single generation per year. Earwigs are nocturnal and feed at night on damaged fruit, leaves, small soft bodied insects, and other foodstuffs. They rarely damage grape leaves.
Monitoring and Spray Thresholds
Rolled up newspaper or cardboard, or flat boards placed on the ground, can be used to monitor earwigs. It might be possible to use these same refuges to enhance their numbers in wine grapes.
Biological Control
Birds, large spiders, wasps and ground beetles prey on earwigs. Earwigs, in turn, feed on the eggs and small nymphs of leafhoppers and on other soft bodied insects.
Cultural Control
Tillage in spring and fall will destroy some of the earthen cells. For table grapes, mowing, tillage, removal of loose bark from vine trunks, and sanitation will remove hiding places and help reduce earwig numbers. They can be kept out of small plantings of table grapes by applying sticky tape or commercial Stickum around trunks and posts. Washing table grapes after harvest will help dislodge many earwigs. Earwigs are less likely to seek refuge in table grape varieties with loose, open fruit bunches.
Chemical Control
Earwigs are sensitive to most insecticides and sprays applied for the control of other grape pests will usually also provide control of earwigs. Commercial earwig baits are also available.September 2010
