The earwig is a slender, reddish-brown insect with distinct pincer-like appendages (cerci) at the end of its abdomen. While their appearance can be alarming, these nocturnal creatures are not dangerous to humans and do not burrow into ears, despite common myths. The central question for gardeners is whether the earwig is a helpful predator or a destructive herbivore, a dilemma stemming from its omnivorous diet which can lead it to both protect and damage plants depending on environmental conditions and population size.
The Beneficial Role of Earwigs
Earwigs function as natural biological control agents, which is the primary reason they are considered allies in the garden ecosystem. They are voracious predators of various common garden pests. Their diet includes soft-bodied insects such as aphids and mites, as well as the eggs and larvae of harmful insects like the codling moth.
They actively seek out and consume small slugs and other soft-bodied larvae, helping to keep pest populations in check. This predatory behavior is valuable in organic gardening systems where chemical reliance is avoided, offering a sustainable method of pest suppression.
Furthermore, earwigs contribute to soil health by feeding on decaying organic debris, breaking down waste material and recycling nutrients.
When Earwigs Become Pests
The earwig’s omnivorous nature means its diet is not solely restricted to pests; they readily switch to plant material when food sources are scarce or when their population density becomes too high. This shift transforms them into a garden nuisance, as they target the most tender parts of cultivated plants. The damage is typically seen as irregular holes chewed in leaves and flowers, giving the foliage a ragged appearance.
Specific plants are susceptible to this herbivorous feeding, including soft fruits like strawberries, raspberries, and apricots, where they chew shallow gouges or holes. They also damage ornamental flowers such as dahlias, zinnias, and marigolds by chewing on the petals. Tender seedlings and the silks of sweet corn are also favorite targets. Feeding on corn silks can prevent proper pollination, resulting in poorly developed kernels.
Managing Earwig Populations in the Garden
Achieving a healthy balance requires managing earwig populations to benefit from their pest control while mitigating plant damage. The first line of defense is habitat management, as earwigs prefer dark, cool, and damp hiding spots during the day. Reducing surface moisture (using drip irrigation where possible) and clearing debris like leaf litter, boards, and dense ground cover near vulnerable plants will limit their preferred habitat.
Simple, non-chemical trapping methods provide an effective way to monitor and reduce excessive numbers. Rolled-up newspaper, corrugated cardboard, or short pieces of garden hose can be placed near affected plants late in the day to serve as daytime shelters. The earwigs that accumulate inside can be collected the following morning and disposed of, typically in a pail of soapy water.
Another effective trap involves using a low-sided can, such as a tuna or cat food can, sunk into the soil so the rim is level with the ground. Filling this with about a half-inch of vegetable oil mixed with a drop of bacon grease or fish oil attracts and traps the earwigs. For sensitive plants, physical exclusion can be used, such as applying a sticky adhesive band around the trunks of fruit trees to prevent the insects from climbing to the fruit.