PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
European earwig
Scientific name
Forficula auricularia (Dermaptera). Can be a
serious pest of some crops, but often just a nuisance
or minor pest in a home garden.
Host range
Earwigs are omnivorous feeders and may feed on a
range of living and dead plant and animal material.
Crops. Many different types of plants, including
ornamentals, eg chrysanthemums, dahlias, zinnias,
fruit, eg grapevines, passion fruit, vegetables, eg
beans, lettuce, rhubarb, field crops, eg barley,
canola, lupins, also mosses, lichens and algae.
Others. Insects. Both dead and living insects
may be eaten. Foodstuffs. Houses close to infested
areas may be entered and flour, starch, sugar, fat
and meat may be eaten. Clothing and carpets.
May enter houses and chew holes in clothing and
carpets. They prey on a wide range of insects
and mites that might occur in a vineyard, consider
its usefulness before using control measures.
Description & damage
Adult earwigs have characteristic pincers
(cerci) at the end of the abdomen and are about
12-20 mm long, brown and have a flattened body.
On the upper surface of both the 2 nd and
3 rd abdominal segments is a pair of pores from
which the earwig can eject a liquid with an
offensive odour to a distance of 7-10 cm. Adult
earwigs have well developed wings but seldom fly.
They are nocturnal and usually found during the
day hiding in flowers, fruit clusters, vegetable
flower head clusters, eg broccoli, rubbish and
under bark. Nymphs are similar to adults except
they are smaller and paler in color.
Plant damage.
European earwigs tend only to become a
problem if populations become large.
Emerging seedlings are damaged to the extent
that re-seeding may be necessary.
Leaves and flowers (petals) may become
ragged in appearance, ragged holes. Fruit and
pods may be chewed. Earwigs also spoil plants
by their presence and their excreta.
Grain and crop seed may be contaminated and
need cleaning.
May be a pest in machine-harvested fruit in
grape vines. Can be a nuisance around packing
sheds.
Diagnostics.
The European earwig is smooth shiny dark
brown with pale yellow legs, pincers and
shoulders and 12-20 mm long. Do not confuse
with other earwigs or other insects, eg
– Black field earwigs which are shiny, black
and 12-15 mm long and which also damage
crops.
– Native beneficial earwigs (several species)
generally have reddish brown foreparts and
legs with a darker abdomen and pincers. They
are widespread and mainly feed on leaf litter
and other organic matter. They rarely cause
any damage to plants. The common brown
earwig is larger than pest species and up to 30
mm long.
– Rove beetles which have no pincers and are
predators living in soil or leaf litter, some feed
on dung and fungi.
Do not confuse damage with that caused by
other chewing pests, eg caterpillars, beetles,
grasshoppers, snails and slugs. Earwigs hide in
crevices and soil during the day, and are not
readily seen.
Pest cycle
There is a gradual metamorphosis (egg,
nymph and adult) with only 1 generation each
year. The female lays 2 batches of 20-80 white
oval eggs, the 1 st in spring and the 2 nd early in
summer. Eggs are deposited in burrows in topsoil
and hatch in 2-3 weeks. Females guard their eggs
until they hatch and may stay for some time with
the small, developing earwigs in the nest. The
young earwigs grow by a series of moults (thought
to be 6 in Australia) until they become winged
adults. The 1 st and 2 nd stage nymphs do not wander
far from the nest and quickly retreat to them if
disturbed. Both nymphs and adults are nocturnal.
‘Overwintering’
As adult earwigs in stubble, under mulch, ground
cover, other plant debris, etc.
Fig. 124. European earwig (Forficula auricularia). Photos NSW Dept of Industry and Investment.
Left: Female (left) with straight pincers and male (right) with curved pincers.
Right: The female earwig in the nest with the newly hatched nymphs.
188 Insects and allied pests - Dermaptera (earwigs)