Distribution. First found in the United States in 1884, ringlegged earwig now is widespread in southern states. It is also known from many northern states, and the southernmost portions of British Columbia, Ontario and Quebec in Canada. Redlegged earwig occurs in Hawaii and has been transported to most other areas of the world, including both tropical and temperate climates. It likely is of European origin.
Host Plants. Ringlegged earwig is omnivorous in its feeding habits, taking both plant and animal material readily. It occurs as a minor nuisance in southern vegetable gardens and in greenhouses, where it nibbles on succulent plants such as lettuce. It is also documented to feed on roots or tubers of radish, potato, and sweet potato, and the pods of peanuts, though this is infrequent and normally of a little consequence. Ring-legged earwig is a voracious predator of insects and sowbugs. This predatory behavior probably offsets the small amount of damage done to plants. It also is highly cannibalistic.
Natural Enemies. The natural enemies of ring-legged earwig seem to be undocumented, though they are likely about the same as those attacking European earwig, Forficula auricularia Linneaus. Cannibalism of eggs and nymphs by adults is an important mortality factor.
Life Cycle and Description. This insect seems not to have been studied under field conditions. Three generations were observed under greenhouse conditions in Ohio—one each in the spring, autumn, and winter months. A complete generation can be completed in 61 days (Klostermeyer, 1942). Thus, under field conditions, it seems probable that at least two generations occur, one each in spring and autumn, at least in warm climates. In Illinois, adults can be found throughout the year except during winter when adults seek shelter deep in the soil. (The ringlegged earwig adult in color figure 178 is referred to on page 196.)
Earwigs are nocturnal. Mating occurs 1-2 days after attainment of the adult stage. Oviposition commences 10-15 days after mating, and requires about three days to complete. The adults construct a small cell in the soil in which eggs are deposited. The female drives the male from the oviposition chamber before eggs are produced. The female protects the egg clutch from mites, fungi, and intruders, cleaning and relocating them if necessary. Maternal care decreases soon after
nymphs hatch, disappearing after about 10 days. The female cannot tolerate the presence of her progeny once she begins production of a subsequent egg clutch. Adults are long-lived, capable of living over 200 days.
The biology of redlegged earwig was given by Klostermeyer (1942), Neiswander (1944), Bharadwaj (1966), and Langston and Powell (1975). Culture was described by Bharadwaj (1966). This earwig was included in the keys by Langston and Powell (1975) and Hoffmann (1987).
These earwigs cause little direct injury to growing vegetable crops, but can feed on both the above-ground and below-ground portions of plants. More commonly, they serve as a contaminant of produce, sometimes defecating on leafy green vegetables. They also can cause injury to stored products such as potatoes and carrots, and are important contaminants of food processing plants (Gould, 1948). These earwigs are important insect predators, and are documented to feed on such diverse prey as caterpillars, beetle larvae, and leafhoppers. Unfortunately, there seems to be no quantitative data on their relative importance.
These earwigs rarely warrant suppression, but are easily killed by most residual insecticides. They also take bait formulations consisting of wheat bran, molasses, and toxicant, as well as many other baits (Neiswander, 1944). For additional information on earwig damage and management, see the section on European earwig, Forfícula auricularia Linnaeus.
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