European earwigs are usually considered to be garden pests, but they rarely damage leafy green vegetables. When they do, they leave many rough irregular holes with a shredded, jagged appearance in the leaves, much like snail and slug damage. They also chew leaves around the edges, similar to the damage caused by caterpillars.
Before treating any pest problem in the garden, it’s important to correctly identify the pest.
Which Pest is Damaging My Plants – Snails, Caterpillars or Earwigs?
How do we identify the real culprit?
- If there are rough, irregular holes in leaves and silvery slime trails present, it’s snails or slugs who are to blame, and not earwigs!
- If leaves are eaten from the edges, and there’s frass (poop) on leaves below the damaged ones, and under the plant, then it’s caterpillars that are the problem.
Caterpillar excrement has the appearance of small, hard brown to black pellets, and is easy to identify. Caterpillars will often be found hiding beneath a leaf, usually lying along the leaf midvein to disguise themselves. The presence of silk webbing, a pupae, or silk cocoon indicates that caterpillars are at work.
Identifying Earwig Damage
Even though European earwigs are scavengers that mainly eat decomposing plant matter, as well as other insects and their eggs, they can also eat the growing shoots of plants and seedlings. Normally, earwigs control many soft-bodied pest insects in the garden and are considered to be beneficial. When their numbers become quite high though, they can cause significant damage to plant seedlings, soft fruit and sweet corn.
When earwigs attack seedlings, they may eat all or parts of the leaves and stem.
They can also damage soft fruit such as apricots, strawberries, blackberries and raspberries by make shallow holes in fruit flesh, or tunnel-like holes that extend deeply into the fruit. They make distinctive holes with rounded edges. Wounds in soft fruit with jagged or straight edges may be caused by birds, or by mechanical damage.
On sweet corn, earwigs eat the corn silks, which prevents pollination, leading to poor kernel development.
Earwigs can also seriously damage ornamental flowers, such as buddleias, dahlias, hostas, marigolds, and zinnias by chewing irregular holes through them.
Since earwigs only attack plants at night, the simplest way to confirm if earwigs are really damaging your plants is to go out at night with a flashlight, and observe them at work!
Where Do Earwigs Hide and How To Discourage Them?
European earwigs are nocturnal, so they roam around and feed at night, and hide during the day.
They tend to congregate together in large groups beneath rocks, mulch, logs and other debris on the ground, as well as under tree bark.
Knowing this, we can manage the pest by using cultural controls, practices which disrupt the environment of the pest, reducing pest establishment, reproduction, dispersal, and survival.
The simplest way to do this is to clean up debris that they hide under, such as piles of rocks, timber, bricks, leaves, and plant debris, or locate it as far away from the garden as possible.
Once the potential hiding places around the garden are minimised, then we can place earwig traps in the garden to capture any of the pests that make their way in there.
How To Make an Earwig Trap That Doesn’t Need Bait
To make a very quick and easy earwig trap, all that’s needed is a 15cm (6”) wide plastic pot, and some cardboard or a whole newspaper.
Just roll the cardboard or newspaper, and push it into the plastic pot so its stays rolled up.
When using a newspaper, make sure the open and not the folded side faces out, so the earwigs can crawl between the pages!
The earwigs will crawl into the gaps during the night, in the morning shake them out into a bucket and dispose of them as desired!
Some gardeners empty the earwigs into a plastic bag and dispose of them in the rubbish bin, but that’s a bit of a waste.
Chickens absolutely love eating earwigs, they are a great source of protein for these birds. Empty the bucket in a clear area and the chickens will clean them up in seconds!
Also, for those who like experimenting with different kinds of earwig traps, please feel free to check out the article – How to Make an Earwig Bait Trap Using Oil, Water and Soy Sauce
More articles on Garden Pests, Diseases and Problems
- University of Minnesota Extension – Earwigs, Reviewed in 2019
- University of California, Statewide IPM Program – Pests in Gardens and Landscapes, Earwigs, published 10/12
- North Carolina Cooperative Extension, What Should I Do About Caterpillars? by Charlotte Glen, Updated on Aug 17, 2015
- Washington State University, Washington State Tree Fruit Extension – Managing earwigs: how and why to conserve in pome fruits and suppress in stone fruits, by Robert Orpet, WSU Entomology, June 2019
Brassica seedlings are always best brought on indoors me thinks.