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European earwigs

Consultant, Sandy Biddulph (Biddulph Rural Consulting), reports finding pest damage in a canola crop near Cootamundra, in the South West Slopes district of New South Wales. Plants at the 4-6 leaf stage were skeletonised and mice were initially thought to be the cause. However, no evidence of mice activity was detected and searching revealed significant numbers of earwigs hiding under clods of dirt. Sandy says the affected area has been treated with grain baits treated with chlorpyrifos to prevent the damage extending further into the paddock.

District agronomist, Phil Bowden (I&I NSW) says earwigs are also present in numerous canola crops around the Cootamundra area. Numbers are generally higher where there is more residual stubble on the ground from last season. Minor levels of damage have been found in some crops, where the earwigs have chewed the margins of cotyledons. Phil says damaged areas are generally quite patchy and most canola plants should outgrow the damage.

In these instances it is likely that the earwigs in question are European earwigs (Forficulina auricularia), which are considered to be the predominant pest earwig in broadacre crops. European earwigs are an introduced species that appear to be spreading in southern agricultural areas, and problems are often associated with high levels of retained stubble. They have been known to cause chewing damage to several crop types including canola, cereals and some legumes.

European earwigs have a shiny brown body with distinctive lighter coloured, yellowish legs. Adults grow up to 20 mm in length. It is important not to confuse European earwigs with other beneficial native earwigs that are also often present in broadacre crops. Research consultant, Samantha Strano (cesar), has identified two species of these beneficial earwigs from samples collected in pitfall traps in a wheat crop near Charlton, in the Northern Country district of Victoria. These have been identified as the native earwigs, Labidura truncata and Gonolabis michaelensi. For more information on earwigs, refer to PestFacts Issue No. 1.

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