Insects of Southern Australian Broadacre Farming Systems - Grains ...

Damage symptoms:
shredded leaf tips or jagged
holes in the leaves are typical of
earwig damage.
Confused with/similar to
Native earwigs and the European earwig are similar to
other earwig species. Earwigs are sometimes confused
with staphylinid beetles, but they can be distinguished
from the latter by the presence of pincer-like cerci.
Distribution, pest status and risk period
European earwigs are an introduced pest into Australia
and were first recorded around 1930. They were recorded
as crop pests in WA in the early 1990’s and have since
been spreading, although their distribution appears to
be patchy and isolated. They are also commonly found
in eastern Australia.
The European earwig’s native climate is cool and relatively
humid. Although adults have wings, they rarely fly and
are mainly spread to new areas and crops by human
activity. They can be transported in contaminated seed,
pot plants, cardboard boxes, machinery and vehicles.
Once introduced, earwigs slowly spread from the
original infestation to neighbouring properties.
Crop and pasture residues on the soil surface enhance
earwig survival and breeding, allowing large populations
to build up during autumn and early winter. Crops and
pastures sown into these high risk paddocks are most
vulnerable to attack by pest earwigs.
Native earwigs are widespread throughout Australia.
They are generally found either individually or in
low numbers under rocks or wood. This contrasts to
the European earwig which is more commonly seen
congregating in high numbers. Native species rarely
exceed 40 mm long and are generally elongated,
flattened and have smooth, shiny bodies that are mainly
brown to black in colour.
Labidura truncata is a common large native earwig
(about 35 mm) that is considered beneficial because
of it’s preference to feed on caterpillars and other softbodied
invertebrates. It captures prey with its pincers
and holds them while feeding.
Crops attacked/host range
European earwigs attack a variety of crops. Crop
seedlings, particularly canola, cereals and pulse crops
are the most susceptible.
Native earwigs are omnivorous, eating a wide variety of
plant and animal material and they are rarely known as
crop pests. Many species live primarily on a diet of plant
matter, both living and decaying. They also consume
dead insects and other organisms.
Damage symptoms
European earwigs often feed at night, starting along
paddock edges and moving deeper into the crop with
time. Shredded leaf tips or jagged holes in the leaves
are typical of earwig damage. In severe infestations,
European earwigs can completely defoliate young
seedlings leaving only stems or bare ground in
the crop (which corresponds to the highest earwig
populations).
European earwigs may become a contaminant of
harvested grain. They shelter in crop windrows (swaths)
and may be collected with the seed at harvest. If earwig
numbers are high, the harvested grain may be rejected
or require cleaning, ultimately reducing profits.
Native earwigs rarely cause crop damage to southern
Australian grain crops.
SECTION 4 COMMON Pest, Beneficial AND EXOTIC Species
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Insects of Southern Australian Broadacre Farming Systems Identification Manual and Education Resource © 2012