Earwigs are insects that often concern gardeners due to their distinctive appearance and habit of hiding in moist, dark places. They are easily recognized by the pair of prominent, forcep-like appendages, known as cerci, extending from the rear of their abdomen. These insects, sometimes called “pincher bugs,” have a varied diet that includes both plant matter and other insects. Whether earwigs damage plants depends dramatically on their population size and the availability of other food sources.
When Earwigs Become Plant Pests
Earwigs become pests when their population density is high or when their preferred food of decaying matter and smaller insects is scarce. Under these conditions, they turn their attention to living plant tissues, causing visible and sometimes extensive damage. They target young, tender growth and plants with soft tissues, such as seedlings, which can be completely destroyed.
Specific plants are particularly vulnerable to earwig feeding, including flowers like dahlias, zinnias, and marigolds. The insects will chew irregular holes in the petals, ruining the aesthetic quality of the blooms. Earwigs also attack soft fruits like strawberries, apricots, and raspberries, often chewing shallow gouges or holes into the ripe flesh. A significant agricultural concern is their habit of feeding on the silk of sweet corn, which can interfere with pollination and lead to poorly developed kernels.
The Earwig’s Beneficial Role
Despite their potential to damage plants, earwigs are an important part of the garden ecosystem. They are skilled scavengers that consume decaying organic matter, such as dead leaves and plant debris. This feeding habit helps break down waste, recycling nutrients back into the soil and contributing to its fertility.
Earwigs are also opportunistic predators that actively hunt and feed on smaller, softer-bodied insects. They consume aphids, mites, and insect eggs, offering a form of natural pest control. In fruit orchards, a healthy earwig population can help manage aphid outbreaks, as their predation often outweighs the minor damage they inflict on the fruit. Maintaining a balanced population allows gardeners to benefit from this predation without significant plant loss.
Identifying Earwig Damage
Earwig damage can be difficult to diagnose because it often resembles the feeding patterns of other nocturnal pests, such as slugs or caterpillars. The most recognizable sign is the presence of irregular, jagged holes or ragged edges on leaves and flower petals. On older leaves, the damage may appear as a tattered network of veins, as the insects consume the softer tissue between them.
Since earwigs are nocturnal, gardeners rarely catch them in the act. They hide during the day in cool, dark, and moist locations, such as under mulch, groundcover, or within plant crevices. To confirm earwigs are the culprits, a flashlight inspection after dark is necessary. The absence of a slime trail also distinguishes earwig damage from that caused by snails and slugs.
Effective Population Management
When earwig populations threaten vulnerable plants, management should focus on non-chemical, cultural controls. A primary strategy is to eliminate their preferred hiding places, including debris, old boards, loose stones, and excessive mulch. Reducing surface moisture is also important, as earwigs are attracted to damp conditions; avoiding overwatering and ensuring good drainage limits their presence.
Trapping is a highly effective and targeted method for controlling localized earwig outbreaks. Simple traps can be made by placing rolled-up newspapers, corrugated cardboard, or short pieces of hose near affected plants before dark. The earwigs will crawl inside for shelter, and the traps can be collected and emptied into a container of soapy water in the morning. Oil pit traps, made from a low-sided can sunk into the ground and filled with vegetable oil and a drop of fish oil, are also very attractive to earwigs.