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Earwigs

By Judy Sedbrook, Colorado Master GardenerSM, Colorado State University Cooperative Extension, Denver County

The European earwig is the most common of the species. It is an elongated, flat insect, reddish-brown to black in color, and 1/2 to 1 1/4 inches in length. The earwig is easily identified by forceps-like appendages (cerci) found at the base of its abdomen. These forceps are used primarily for defense and during courtship. The name "earwig" originated from the widespread superstition that the insects purposely crawl into the ears of sleeping persons and bore into their brains. In fact, other than an occasional pinch, earwigs can't harm people.

Earwigs are primarily scavengers of dead insects and rotted plant materials but may also feed on live plants. They are a natural enemy of some mites and aphids. Earwigs can become a problem in the garden, feeding on the roots and leaves of flowers, vegetables and shrubs. Common targets include marigolds, dahlias, zinnias, roses, lettuce, and strawberries. They may also feed on corn tassels and blossoms, reducing kernel set. Plants defoliated overnight, in the absence of pests in daylight or the telltale signs (slimy trails) of slugs, may have been attacked by earwigs.

Earwigs are most common in the summer and most active at night. During the day they usually find shelter in dark, moist places beneath stones, boards, sidewalks, debris or in the soil. Since they multiply fairly quickly, an infestation can number in the thousands

When dry weather sends them in search of moisture, earwigs can become an indoor pest as well. Here they will seek shelter under rugs, cushions, and baseboards, and in dark, damp crevices, especially in basements. After entering houses, they feed on sweet, oily or greasy foods or houseplants.

CONTROL:

Prevention:

  • For best control indoors, one must first control earwigs outdoors. Eliminate damp, moist conditions in crawl spaces under houses, around faucets, around air-conditioning units and along house foundations.
  • Create a clean, dry border using gravel or stone immediately around the foundation wall. Rain gutters and spouts should carry water away from the house foundation.
  • Eliminate refuges such as ivy, weeds, piles of yard debris and leaves.
  • Check entry points, door thresholds, windows and screens for a tight fit.
  • Caulk cracks and crevices around windows, doors, cables coming into walls, and in the foundation itself.
  • Earwigs are attracted to light. Reduce lighting around doors, windows and other potential entry sites. Use lights that are less attractive to insects such as sodium vapor yellow lights.

Natural:

  • Encourage natural earwig predators including toads and birds.
  • Construct earwig traps out of shallow tin cans. Fill the cans with a half-inch of vegetable oil and place them in the garden. Empty and refill as needed.
  • Earwigs can also be trapped in cardboard boxes baited with oatmeal or bran. Poke a pencil-sized hole in the sides near the bottom for entry.
  • Effective earwig traps can also be made of rolled newspaper or old hose pieces. Place these tubes near plants at sunset. Empty into a bucket of water each morning.
  • Sweep up or use a vacuum cleaner on earwigs found inside the home. Once inside the home, they will eventually die without treatment.

Chemical: Chemical control are most effective when applications are made outdoors, since the problem originates outdoors.

  • Apply insecticides around the building foundation, in subfloor crawl spaces, and to flowerbeds and turf within a couple of yards of the building. Mulches in such flowerbeds should be treated thoroughly. Always be sure to read the label and follow instructions carefully.
  • Apply sprays in late afternoon, if possible, so that residues are fresh when the earwigs become active in the evening.
  • Earwigs may seek protection beneath the soil. There are emulsifiable or wettable insecticides labeled for use on earwigs. Be sure to use enough water to ensure that the chemical is carried down to where the earwigs are active.
  • Indoors, use aerosols or dusts registered for indoor use. Apply to baseboards, beneath cabinets, and in other hiding places at floor level.
  • Insecticides and traps used for cockroaches are also effective indoors against earwigs.
  • Earwigs indoors can be sprayed with spray-and-wash cleaners which will kill on contact.

For further information on earwigs, see CSU Fact Sheet 5.533.

Photo: Judy Sedbrook

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Date last revised: 01/05/2010