Earwigs: Don't Wig Out
Are you slightly intimidated by the small, but menacing-looking earwig? Perhaps it's their frantic emergence from an artichoke or head of lettuce that creeps you out? Okay, maybe it's just the pincers. Despite their ferocious appearance and old myths [about crawling in your ear and burrowing into your brain], earwigs are harmless to humans.
One of the most interesting things about earwigs is that the females care for their young -- nurturing, feeding and protecting them during the first stages of life. Females lay 20 to 50 eggs, so that's a lot of mouths to feed!
There are approximately 22 earwig species in the United States.1 In the western and northern regions of the United States, the primary pest species is the European earwig (Forficula auricularia),1,2,3 which was introduced into North America in the early 1900's.2
Earwigs are easily recognized the pair of pincers -- also called forceps or cerci ("sir-see") -- at the tail end of the body.1,2 Male earwigs have curved pincers while the female pincers are smaller and straighter. Besides pinching in defense and to capture prey, the pincers are used to probe crevices,4 and fold and unfold wings.4,5
The adult European earwig is somewhat flat, reddish brown, and ranges from 1/2 to 3/4 inch long.6,3 Earwigs have two sets of wings, but they rarely fly.2,4 The top pair or wings are short and tough. Tucked under these are longer membranous wings. 3,4 Young earwigs resemble their parents but are smaller, lighter in color, and lack wings.2
In the fall, male and female earwig pairs dig into the soil and hibernate. Sometime between fall and spring the female lays between 20-50 round, white eggs in cells dug in the upper few inches of the soil.4,3 Small white nymphs hatch from the eggs.2
It's unusual for insects to nurture their young, but female earwigs take care of the eggs and young offspring2,6 Females will move, lick and rotate the eggs. They also bring food to the young nymphs6 and use their pincers to protect them from predators.4,5 Young earwigs go through 4-5 nymph stages before becoming adults.1
Earwigs usually feed at night and hide during the day seeking moist, dark places such as dense growth of plants, flower pots, boards, mulch, and even in fruit damaged by other pests.1,2
Earwigs are omnivores, eating a variety of dead and living organisms. Earwigs can be beneficial because they feed voraciously on aphids and insect eggs.2 They'll also eat mites and fleas.6
Unfortunately, they can sometimes devastate seedlings and annual flowers and seriously damage soft fruit and sweet corn.2 Older plants can tolerate some munching.2,6
Some of their favorite garden foods include: 1,2,6
- Flowers: dahlias, marigolds, zinnias, petunias
- Vegetables: lettuce, cabbage, corn silk, foliage of beans, peas, potatoes
- Fruit: strawberries and soft fruits such apricots and peaches (stone fruits)
On leaves, earwig make many small, irregular holes that give the leaf a ragged appearance - not unlike damage caused by slugs and caterpillars.6 In soft fruit, look for shallow gouges or deep holes.2,3
Managing Earwigs in the Garden
Managing earwig populations is an easy 3-step process. First, figure out who is actually the pest. Second, eliminate the conditions or environment that earwigs like best, especially in preferred areas like your new bed of lettuce seedlings. And third, reduce populations through an active trapping program.
Find The Real Culprit
If you find that you have excessive damage on your plants, go look for the culprit. If you see slime on the plant or surrounding ground it could be snails or slugs eating your plants. Caterpillars you may leave poop, pupae or webbing. To be certain go out at night with a flashlight to see who is actually feeding on your plants. You can use traps to monitor earwig populations, but just because you catch earwigs does not necessarily mean that they are the culprits.2 Earwigs can be present in large numbers and not be causing much damage.5
Altering the habitat around your garden will reduce earwig damage. Here are some tips:
- Get rid of their hiding places: boards, weeds, wood piles, plant debris, leaf litter, and any other objects that create dark, moist hiding places.1,2
- Do not plant dense ground covers, such as ivy, next to vegetable or flower gardens.2
- Raise vulnerable seedlings indoors until they are able to withstand some munching.5 Or start them outdoors on a table with legs protected by sticky barriers.5
- Protect stone fruits (such as apricots and peaches) by opening up the area around the base of the tree: Trim suckers, clear weeds, and take out heavy ground covers. The University of California earwig factsheet offers more detail for these trees.2
- Enlist a couple of ducks or banty chickens - great for the orchard or yard, but keep them out of the garden.7
- Some sources advise against the use of heavy organic mulch because it provides harborage.1,2 The opposing view is that compost mulch offers earwigs a diverse hunting and feeding grounds that will distract them from your plants.5
Reduce Nuisance Populations:
Trapping is an effective, easy and low-tech way to reduce earwig populations. Rolled up newspapers or corrugated cardboard, low-sided cans such as tuna cans filled with oil, burlap bags, boards, an 8-10 inch piece of garden hose and a bamboo tube can all be used as traps. If you really want to build something, you can do that too.
Just before dark, place numerous of traps on the ground around the garden or under shrubbery or ground cover. In the morning, when earwigs go into hiding, shake them out the traps over a pail of soapy water (except the low-sided traps which can just be emptied in the compost pile if the earwigs are dead).2 If you use burlap bags or boards as traps you have the less appealing option of crushing them before they scurry away.3 Keep trapping until you don't catch any more earwigs2. Be creative. Create your own trap, just keep in mind that earwigs prefer moist, tight, dark places.
- Newspaper: A rolled-up newspaper2 held with a rubber band.
- Bamboo: Lengths of bamboo with ends should be open.2
- Cardboard Box: Punch pencil-size holes along bottom edge of cardboard box. Bait with oatmeal or bran.4 (pictured above)
- Corrugated Cardboard: Lay out pieces of corrugated cardboard2 or roll it up and hold with rubber band. Moistening the cardboard might help.
- Hose: 8-10 inch pieces of garden hose1
- Low-sided Can: Use a tuna or catfood can. Add 1/2 inch tuna fish oil or vegetable oil with drop of bacon grease,2 or even vegetable oil alone.
- Margarine Tub: Use a margarine tub or similar container. Punch holes along the top edge of the tub, add 2 inches soy sauce and 1 tablespoon of oil, cover with top and sink in ground.8 This trap might be a good option to the low-sided can especially if you are catching beneficial bugs or attracting bigger beasties.
Managing Earwigs in the Home
Earwigs also show up in homes, either brought in on produce, garden materials or entering on their own through cracks and crevices in the building. Inside, they are a harmless nuisance.2 They don't breed indoors, so a continuing problem suggests that they are getting in from outside.6 Here are a few tips for eliminating earwigs in your home.
- Caulk cracks, crevices, and other openings in the foundation or around the outside of the house.
- Manage moisture around the building by fixing leaky faucets and air conditioners, repairing drain spouts, directing water away from the foundation,4 and ventilating crawl spaces.2 Avoid overwatering.1
- Outside, lay traps in likely hiding places.1
- Caulk and weatherstrip around doors and windows.1
- Establish a clean, dry border right next to your foundation. Stone mulches are less attractive than thick organic mulches. Remove debris, leaf litter, firewood, and dense ground cover.1,2
- If you have earwigs hiding under well caps, replace them with tight-fitting caps that will prevent any insects from falling into your well.6
- Some species of earwigs are attracted to lights, so you should reduce lights around potential entrances such as windows and doors. Use yellow lights instead of white.4
- Vacuum up or sweep up any earwigs inside your house,2,4
As you head into your garden, armed with every trap we've described in these pages, remember that earwigs serve a critical function not only in the larger ecosystem but in your garden as well, even if they do look scary. Protect your vulnerable plants, reduce earwig populations and habitat where you need to, but leave some to eat up insects, as well as to feed the birds and other critters.2 And remember how hard those earwig mothers worked to keep those babies alive!!
- University of Illinois Extension, Integrated Pest Management. 2004. Earwig. http://ipm.uiuc.edu/hyg/insects/earwig/index.html
- Flint, M.L. 2002. Earwig. Pest Notes Publication 74102. University of California Agriculture and Natural Resources. http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74102.html
- Antonelli, AL Rv. 2006. European earwig prevention and control Extension Bulletin 1206E. http://cru.cahe.wsu.edu/CEPublications/eb1206e/eb1206e.pdf
- Lyon, WF. Undated (1994?) . Earwigs: HYG-2068-94. Ohio State University Extension. http://ohioline.osu.edu/hyg-fact/2000/pdf/2068.pdf
- Olkowski, W.,S Daar, and H. Olkowski,. May, 1991. Common-Sense Pest Control. Taunton Press. Newtown, CT.
- Pellitteri, P.J. 1999. Controlling Earwigs. University of Wisconsin Cooperative Extension. Publication #A3640. http://learningstore.uwex.edu/pdf/A3640.pdf
- Resources for Idaho: HomeWise. Week of July 26,1999. University of Idaho. http://info.ag.uidaho.edu/homewise/homewise_072699.htm (link no longer active)
- Master Gardeners of Santa Clara County. January 2003. Starting Seeds at Home. University of California Cooperative Extension. http://www.mastergardeners.org/publications/startingSeedsAtHome.html
Murphy, Karen. "Earwigs."
Eugene, OR: Northwest Coalition for Alternatives to Pesticides, July 2007. Links updated October 2010.