How to Make an Earwig Bait Trap Using Oil, Water and Soy Sauce

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The European earwig (Forficula auricularia) is one of our most common earwigs found worldwide in gardens. These insects are scavengers, and they are omnivores –  they are voracious feeders on soft-bodied insects such as aphids and insect eggs, they also prey on mites, spiders, and various insects, so they do serve a role as beneficial insects, and they also eat plant materials, both living and living or dead.

When earwigs consume decomposing plant material, they help clean their natural environment, but when they feed on living plants, leaving numerous irregular ragged holes and chewed edges on vegetable leaves, eat the leaves and even stems off seedlings, or leave shallow holes in soft fruit, such as strawberries, raspberries, blackberries and apricots, they are considered a pest in the garden.

One way to control earwigs in the garden is to use a baited trap. This simple trap is buried in the soil, with a small cover over it to prevent the trap filling water when it rains. It uses soy sauce as the attractant (bait) to draw the earwigs in, and water with a layer of vegetable oil on top, so when the earwigs fall in, they can’t swim and crawl out, and they drown in the container.

To make the earwig bait trap, you will need:

  • 2 tablespoons (30ml) of soy sauce
  • vegetable oil of any kind
  • any small container that is reasonably deep, such as a small jar, plastic yogurt container, tuna tin or similar
  • a cover for the small container,which is reasonably larger than the container, such as a lid from a larger jar, or a plastic plant pot saucer (large plastic lids work well)

Set up the bait trap as detailed in the diagram and the instructions below:

earwig-oil-water-soy-bait-trap

Step 1 – Fill a small container 1/3 full with water. Use a small yogurt container, small jar, tuna tin, large pill bottle or anything that is fairly deep.

Step 2 – Add 2 tablespoons (30ml) of soy sauce.

Step 3 – Pour in vegetable oil to form a layer on the surface of the water, use just enough oil to cover the surface in a thin layer. Some instructions suggest using a layer of oil 6mm (1/4”) thick, but that may be too much.

Step 4Bury the container in the soil, leaving the top sticking up a slight amount above the soil, to stop the surrounding soil from falling into the trap, which will render it ineffective.

Step 5Cover the trap with a large plastic lid or plant pot saucer to protect it from rain, so it doesn’t get flooded and washed out. Use a cover larger than the container, so it extends a reasonable way around the edge of the small container to act as a kind of shelter. Prop up the cover with 4 stones placed around the jar. The stones should be large enough to elevate the cover above the soil surface, leaving a small gap all the way around between the container and the cover for the earwigs to crawl under.

Step 6 – Leave the bait trap in place for a few days, and it will fill with earwigs. Dump the resultant mess into the compost, and then refill the container for the next round.

Earwigs are nocturnal, they come out at night to feed. These traps can be placed in the garden near piles of wood, rocks or other garden debris where earwigs hide during the day, or in garden beds where new vegetable seedlings are planted to protect them from earwigs.

References

  • Missouri Department of Conservation – Field Guide, Earwigs: Forficula auricularia, Euborellia anulipes, and others.
  • Government of Western Australia, Department of Primary Industries and Regional Development (DPIRD), Agriculture and Food – Management of European earwig, last updated: Thursday, 2 July 2020.
  • North Carolina State University, N.C. Cooperative Extension, Center for Integrated Pest Management  – European Earwig: Pest, Beneficial or Both? by Ryan Adams
  • Pennsylvania State University, Penn State New Kensington – Species pages, European Earwig

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