The European earwig (Forficula auricularia) is a common garden insect that becomes a significant pest when populations grow too large. While earwigs are mostly nocturnal scavengers that consume decaying plant matter and other pests like aphids, they readily feed on soft plant tissues, flowers, and fruits, causing noticeable damage. Addressing an earwig problem requires a targeted approach that modifies their environment and employs direct control methods to protect vulnerable plants from nighttime feeding.
Confirming Earwig Damage
Identifying the correct culprit is the first step, as earwig damage can often be mistaken for feeding by slugs, snails, or caterpillars. Earwigs leave irregular, ragged holes in leaves and petals, frequently chewing around the edges of foliage, giving it a shredded appearance. This damage is distinct from the larger, smooth-edged holes left by slugs and snails, which also leave a silvery slime trail. Earwigs also damage soft fruits like strawberries and raspberries, leaving shallow gouges, and climb plants to feed on flower buds and corn silks. Since earwigs are active only at night, confirm their presence by inspecting plants with a flashlight one to two hours after sunset.
Changing the Environment for Prevention
Earwigs thrive in dark, cool, and especially moist environments, making habitat modification a highly effective long-term control strategy. Reducing the amount of damp shelter available will naturally lower the earwig population in the immediate vicinity of your plants. This involves removing ground-level debris such as piles of leaves, old wood, flat stones, and other clutter that provides daytime hiding spots. Modifying watering practices also makes the area less appealing; switch to drip irrigation instead of overhead sprinklers, and water early in the morning so the soil surface dries out by evening. If using mulch, keep the layer thin and pull it back a few inches from susceptible plant stems to create a dry zone.
Physical Trapping and Removal Techniques
Active removal through trapping exploits the earwig’s instinct to seek dark, tight shelter before dawn. Place these physical traps near damaged plants before nightfall and check them every morning for maximum effectiveness. Simple shelter traps can be made by placing rolled-up newspaper, corrugated cardboard, or short sections of garden hose on the soil surface; earwigs crawl inside these objects to hide during the day. In the morning, shake the contents of these traps over a container of soapy water to drown the trapped insects. Another effective method is the oil-pit trap, which uses a low-sided container, such as a tuna or cat food can, partially filled with about half an inch of vegetable oil. The can should be buried so the rim is flush with the ground, and the oil can be mixed with bacon grease or soy sauce to act as an attractant.
Targeted Biological and Chemical Controls
When environmental changes and trapping are not sufficient to manage a severe infestation, targeted applications of specific products can provide further control. Diatomaceous Earth (DE) is a natural, mechanical control made of pulverized fossilized diatoms. This fine powder works by scratching the earwig’s waxy exoskeleton, causing the insect to dehydrate and die. Apply DE as a light dusting around the base of plants, but note that it becomes ineffective once wet and must be reapplied after watering or rain. Organic insecticides may be used sparingly on vulnerable plants as a last resort.
Chemical Options
Products containing spinosad, derived from a naturally occurring soil bacterium, can be applied as a bait or spray and are effective against earwigs. Pyrethrins, extracted from chrysanthemum flowers, are another option. Use these treatments with caution and apply them late in the evening to avoid harming beneficial insects that are active during the day.
Biological Control
Introducing beneficial nematodes to the soil is a biological control method. These microscopic worms infect and kill earwig young, helping to disrupt the pest’s life cycle.