Earwigs

Earwigs are omnivorous, they feed on small invertebrates and plant material. They can help reduce some pest problems but they will also damage flowers and young leaves of clematis, dahlia and chrysanthemums and occasionally other plants.

Earwigs and the damage causes to a cosmos flower. Credit: RHS/Entomology.

Quick facts

Common name Common earwig
Scientific name Forficula auricularia
Plants affected Mainly dahlia, clematis and chrysanthemum
Main symptoms Young leaves and flower petals are eaten. Earwigs will be present on the plants after dark
Most active May-September

What are earwigs?

Earwigs are yellowish brown insects, up to 13-15 mm long (about ½in), that have a pair of distinctive pincers or forceps on their rear end.

Symptoms

  • Flower petals and young leaves can be eaten; older foliage is sometimes reduced to a tattered network of veins
  • Inspect plants by torchlight on a mild night to find earwigs feeding on the flowers and foliage 
  • Earwigs hide in sheltered places during the day and emerge after dark to feed
  • Other nocturnal pests that might be responsible are slugs, snails or caterpillars

Control

Prevention

  • Avoid growing susceptible plants against wooden fences, which provide daytime hiding places

Non-chemical control

  • Trap earwigs by placing upturned flower pots loosely stuffed with hay or straw on canes among plants being attacked
  • Every morning shake out the pots and remove the earwigs
  • This may not protect plants when earwigs are abundant, but it is a useful means of monitoring their numbers

Chemical control

  • Before resorting to chemicals remember that earwigs are omnivores and can be of benefit in the garden by eating small insect pests
  • If damage is extensive, spray at dusk on mild evenings when earwigs are likely to be active with deltamethrin (e.g. Bayer Sprayday Greenfly Killer) or lambda-cyhalothrin (e.g. Westland Resolva Bug Killer)
  • Do not spray plants in flower due to the danger to pollinating insects.

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Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Biology

Earwigs overwinter as adult insects in the soil and other sheltered places.

  • Batches of eggs are laid in the soil in midwinter and again in early summer
  • Female earwigs remain with their eggs until they have hatched
  • The nymphs look like smaller versions of the adult insect 
  • Earwigs are one of the few insects where the adults show some parental care, protecting the nymphs from predators
  • Earwigs come out to feed at night during late spring to early autumn, and prefer soft tissues to older foliage
  • Earwigs also feed on aphids and other pests and can help reduce infestations.
  • They can eat small insects and eggs, as well as plant material

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