European earwigs

Agronomist, Kerry Hammond (Landmark), has reported earwigs attacking canola plants near Harden, in the Southwest Slopes of NSW. The earwigs are likely to be European earwigs (Forficula auricularia), which are generally not a widespread problem. Kerry says that this is the first time she has heard of earwigs causing significant crop damage in the region. European earwigs can devastate patches of canola crops, and are difficult to control with conventional insecticides. Young seedlings are particularly susceptible to attack.

European earwigs are an introduced species that have been spreading in southern agricultural areas, probably by transport in hay, machinery or household pot plants. They are an emerging pest of canola, mainly on heavier soil types. It is believed that their numbers have increased in recent years due to intensive cropping and stubble retention, which improves the habitat for earwigs.

Adult European earwigs range from 12-20mm long, are smooth and shiny dark brown with pale yellow legs. They have distinctive “pincers” that protrude from their rear end and look very similar to the native earwig, which is commonly found around household leaf litter. Native earwigs rarely damage plants and are generally not significant pests. Native earwigs look similar to European earwigs but are reddish-brown and the abdomen and pincers are darker in colour.

European earwigs are nocturnal (therefore monitoring should be conducted at night) and shelter in dark spaces, such as under trash or cracks in the soil, during the day. They feed on the developing leaves of canola seedlings, slowing down plant development, and in some cases destroying the plants. Irregular shaped holes are typical of earwig feeding. They can also chew through the pod, causing seed development to stop, and contaminate windrows at harvest time.

European earwigs tend to only become a problem if populations become large. Currently no chemicals are registered for the control of earwigs in canola. Growers have had success controlling earwigs with synthetic pyrethroids. Reducing stubble residue may lead to a decrease in earwig numbers. The burning of stubbles in paddocks known to harbour earwigs has been shown to give satisfactory control but this has limited application as it can lead to wind erosion. See your local agronomist in relation to spray/bait recommendations.

Paul Horne (IPM technologies) says it is important to know the difference between this species and the common brown earwig (Labidura truncata). The common brown earwig is a large native earwig that is a predatory species. It is beneficial to agriculture; preferring to feed on soft-bodied caterpillars. Paul says the common brown earwig may also attack redlegged earth mites and lucerne flea, and can be identified by the presence of an orange coloured triangle behind the head on the elytra or ‘wing-case’. Click here for further information and to see an image of the common brown earwig.