Q Is there more than one type of earwig in Britain?
A The earwig usually seen in gardens is the common earwig (Forficula auricularia), one of four species native to Britain. Other kinds may sometimes be locally significant, including tropical ones that have been known to set up home in heated greenhouses, bakeries and other warm places. Ordinary earwigs appear indoors too. They are too well-known to need describing, but the males (up to 17mm) are larger than the females (up to 14mm) and the young or 'nymphs' are paler and smaller.
Caption: Earwigs are often found on flowers
Q Will their pincers 'bite'?
A They are not strong enough to break the skin. Their pincers seem to be used more for display and in breeding than for defence or attack. Females have almost straight pincers and males have curved ones.
Q What do they feed on?
A They eat a very wide range of food, including plants, animals and decaying organic material. Aphids and other insects, mites and nematodes, feature in their diet. Generally earwigs seem to do more good than harm.
Q What damage do they do?
A Growers of show dahlias and chrysanthemums may find earwigs ruining prized blooms but otherwise the damage is usually trivial. Only occasionally do their numbers reach levels where the damage they do is worth bothering about. Tender parts of plants are sometimes nibbled, with young leaves and blooms being the favourite plant food. Typical signs are ragged petals and skeletonised leaves. Favourite foods are cinerarias, dahlias, clematis, chrysanthemums, zinnias and other flowers.
If earwigs are to blame you will find them nearby, hiding in plant material, hollow canes, cracks in posts, coarse mulch, beneath stones, pots and containers. They will also hide in flowers and foliage. Seedlings of vegetables are attacked. However, they are seldom a serious pest. In fact, the damage is often started by slugs, snails, caterpillars, slugworms, sawfly larvae, capsids, birds and other pests, with earwigs coming along later to get a 'free' meal, and getting blamed for the original problem.
One example of this is when they turn up in holes in fruit. They seldom injure undamaged fruit, but when birds peck holes in apples, the earwigs move in and enlarge the hole. Cracked and russeted fruit can also suffer from earwigs' attentions. Earwigs can puncture fruit on their own. This is seldom serious, but the punctures can let in rot.
When gathering fruit, flowers and vegetables earwigs can be a nuisance. They not only get in the way, but also nest in sheltered spots, in between fruit in clusters or in sweetcorn heads for example, soiling the produce with their black droppings. They can even nest in boxes of stored fruit such as apples.
Q I've heard earwigs can fly. Is this true?
A They have a pair of delicate wings that they seldom use. The wings are hidden away under leathery covers. Usually they prefer to move by running. This means that if you remove earwigs, they do not return quickly.
Q What more can you tell me about them?
A The adult earwigs take shelter in the soil or rubbish piles over the winter. The female lays about 60 eggs after mating and looks after them in a chamber in the soil until they hatch in early spring. The wingless young or nymphs feed and develop through four stages until they finally reach adulthood in early summer. At first they remain in the nest chamber and are cared for by the female. Not only does she feed them with regurgitated food, but she also licks them to keep them free of fungal spores. Later they move out and fend for themselves. The adult females that survive the winter may also lay a second batch of eggs in late spring or early summer. The young from this brood mature in late summer.
Q How do I know if earwigs are to blame for damage?
A Since they only come out at night the easiest way is to inspect plant damage after dark with a torch. If earwigs are the culprits you will catch them in the act. Slugs and snails leave tell-tale slime trails behind; caterpillars can be shaken out of foliage and leave their dark droppings where they have been feeding.
Q What can I do about them?
A You can take advantage of their habit of seeking daytime shelter to trap them. They like really tight spaces to hide in. Make traps of pots filled with straw or corrugated cardboard and place this on top of stakes or canes holding up affected plants, or around the base of the plants.
Other possibilities are: using lengths of garden hose cut on a slant, hollow bamboo canes, rolls of corrugated cardboard, pieces of sacking placed on the ground, or boards with grooves in them placed groove-side down on the ground. Next morning shake the earwigs out of the traps into a bucket. If you wish to kill earwigs, drown them in soapy water.
Q Can I discourage them?
A Reducing their daytime hiding places may work. Don't use coarse mulches, of bark or polythene sheeting for instance. Clear up piles of plant material and any planks or stones beneath which they could hide. Cultivate bare soil to a fine tilth to destroy underground spaces in which they can breed or hide. Do this in the winter and you should reduce any earwig problems for the following year. Replacing grass with bare earth around fruit trees will deter earwigs and improve the growth of the tree.
Q Can I spray them?
A They are a hard pest to control by spraying and it is not that effective.
Q What organic methods can I use?
A Earwigs are a free form of biological control of other pests. If you find them causing damage, you could collect them up and let them loose elsewhere. Not only are they unlikely to be replaced or return, but will stay in the part of the garden where you let them loose. Ones from your greenhouse could be very useful, killing pests in shrub borders, for example.
Q How do I keep them out of the house?
A Shake out garden produce, laundry and garden furniture before bringing it indoors. Fill in gaps in masonry and around windows and doors, and fit tight-fitting draught excluders to keep them out. Make sure borders around the house are free from plant debris and loose leaves.