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Earwigs

Earwigs may present problems for some growers this season as they are also likely to be favoured by higher stubble loads that provide an ideal habitat for survival. Grower, Bronwyn Hunt (Merriwa Pastoral Company), has reported finding earwigs in pitfall traps in a paddock near Kerang, in the Mallee district of Victoria. Bronwyn says earwigs are generally not seen in this region and she suspects their presence is due to high rainfall throughout summer. Some of the earwigs have been identified as the native common brown earwig, (Labidura truncata) which is a beneficial insect. This species mainly feeds on soft-bodied insects, such as caterpillars, lucerne flea and mites. The common brown earwig can be distinguished by the presence of an orange colored triangle behind the head on the elytra or ‘wing-case’.

At this stage Bronwyn says there have been no European earwigs (Forficulina auricularia) found. European earwigs are an introduced species that appear to be spreading in southern agricultural areas. It is believed their spread is at least partly due to increased levels of stubble retention. In the past they have been found damaging canola, cereals and some legume crops. European earwigs chew developing seedlings and slow plant development. The typical appearance of damage is shredded leaf tips and/or irregular holes in leaves. European earwigs range from 12-20 mm long, are smooth and shiny dark brown in colour with pale yellow legs. It is important to distinguish earwig species in order to make the most appropriate management decision and accurately assess the risk of attack to emerging crop seedlings.

Control options for earwigs are limited, however there is some evidence that insecticide seed treatments such as fipronil will help crop seedlings withstand attack. Cracked grain baits (wheat or sorghum) containing chlorpyrifos and sunflower oil may also be used to control pest earwigs.

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