Earwigs are common garden insects recognizable by the forceps-like pincers, or cerci, protruding from the rear of their elongated, reddish-brown bodies. They are nocturnal, hiding in dark, moist crevices during the day, which can make their presence a mystery until damage appears. Earwigs are omnivorous, meaning their impact on a garden ecosystem is complex and highly dependent on their population density and available food sources.
Earwigs as Beneficial Predators
Earwigs are omnivorous, meaning their diet includes both plant matter and other insects, which positions them as effective biological control agents. Their predatory activity is a significant positive contribution, particularly against soft-bodied pests that can rapidly damage plants. They actively hunt and consume common garden nuisances like aphids, mites, and the eggs and larvae of various pest insects.
Studies show that earwigs can substantially reduce aphid populations, targeting spider mites, small caterpillars, and tiny slugs. This consistent consumption of pests often provides a natural balance that outweighs the minor plant damage they might cause in an otherwise healthy garden.
Beyond predation, earwigs contribute to soil health by feeding on dead or decaying organic matter, such as fallen leaves and plant debris. This scavenging behavior helps to recycle nutrients back into the soil, improving fertility and breaking down material that could otherwise harbor disease.
When Earwigs Become Pests
While earwigs provide pest control benefits, they can switch to eating plants when their populations become too large or when preferred insect prey becomes scarce. Problems generally arise when numbers explode, leading to noticeable damage on vulnerable garden plants. The damage is primarily caused by their nocturnal feeding habits, so the culprits are rarely seen in action during the day.
Earwig feeding leaves distinct patterns, often appearing as small, irregular holes in leaves, which can be mistaken for slug or caterpillar damage. They target tender, new plant growth, including seedlings, which they can completely defoliate, and the petals of flowers like zinnias, marigolds, and dahlias. On maturing produce, earwigs tunnel into soft fruits, such as strawberries, raspberries, and peaches, causing shallow gouges or deep holes.
A particularly problematic area is the vegetable patch, where earwigs will chew on corn silks, interfering with pollination and resulting in poorly developed kernels. The presence of moisture and dense hiding spots, such as heavy mulch, leaf litter, and ground covers, encourages large population build-ups. Observing the damage at night with a flashlight is the most accurate way to confirm that earwigs are the specific pest.
Strategies for Population Control
The most effective approach to managing earwigs is to monitor population levels and implement control methods only when the damage surpasses an acceptable threshold. The first step in population management is habitat modification, which involves reducing the number of damp, dark hiding places they seek during the day. This includes removing piles of boards, stones, debris, and excessive mulch from around vulnerable plants.
Adjusting watering practices makes the environment less hospitable, as earwigs thrive in moist conditions. Switching to drip irrigation keeps the soil surface drier, and watering in the morning allows the soil to dry out by nightfall. Exclusion techniques, such as banding tree trunks with a sticky barrier, can prevent earwigs from climbing to feed on soft fruit.
Simple, non-toxic traps are highly effective for reducing high populations without harming beneficial insects. Traps serve as ideal dark daytime shelters, allowing earwigs to be collected each morning and disposed of in soapy water.
Trap Options
Traps can be created using:
- A rolled-up newspaper.
- A short piece of garden hose.
- Bamboo tubing placed on the soil.
- A low-sided can filled with vegetable oil and a drop of bacon grease or fish oil, which attracts the earwigs to drown.