Description of the Pest
The introduced European earwig (family Forficulidae) is the most common of several earwig species that can occur in avocado. Adults are about 0.75 inch long, reddish brown, and have a pair of prominent tail appendages that resemble forceps. Most species have wings under short, hard wing covers, but earwigs seldom fly. Immature earwigs resemble small, wingless adults.
Earwigs feed mostly at night and hide during the day. Common hiding places include bark crevices, mulch, topsoil, protected (touching) plant parts, and under trunk wraps. Females lay masses of 30 or more eggs in soil. Nymphs are whitish and remain in soil until their first molt, after which they darken and begin searching for food. Earwigs generally have one or two generations a year. They can be active year round.
Earwigs feed on dead and living insects and insect eggs, other organisms, and on succulent plant parts. Earwigs occasionally damage buds and leaves on young or newly grafted trees. They can be especially problematic on trees with trunk wraps or cardboard guards. The cause of damage can be difficult to distinguish from that of other chewing pests that hide during day and feed at night, including brown garden snail, Fuller rose beetle, and June beetles.
If you suspect that earwigs are causing damage, lift and shake or sharply tap any trunk wraps and look for earwigs dropping to the ground, where they quickly scurry for cover. Alternatively, place a folded newspaper or burlap bag near the base of several trees with chewed foliage. Check these traps or earwig hiding places the next morning.
To manage earwigs use baited traps or remove hiding places. Cans with sardine or tuna fish oil are highly attractive to earwigs, which will climb into containers and drown. It may be necessary to cover liquid traps with heavy screening to exclude feeding by domestic and wild animals drawn to the fish odor. Remove trunk wraps where pests hide when wraps are no longer needed, thereby reducing earwig numbers. Earwigs rarely are abundant enough to warrant chemical treatment, except on young trees bordering uncultivated areas. Check with your cooperative extension advisor or county agricultural commissioner about the registration status of baits for treating earwigs.