First detected in Australia in the 1930s, the introduced European insect species can be confused with the native predatory common brown earwig, which is usually larger, with an orange triangle on its back.
In South Australia, the citrus lobby has been working with biological services experts to help growers detect, monitor and control European earwigs.
Entomologist Dr Paul Horne and entomology consultant James Altman said the insects were widespread throughout the country, and mostly active at night during the cooler months.
“They are considered pests in many crops but have also been regarded by some as useful biological control agents of pests such as light brown apple moth, scales, aphids and mealybugs,” they said.
“They produce an aggregation pheromone and can develop into high numbers, forming large groups in tight spaces away from direct sunlight.”
Check crops early
Citrus SA president Mark Doecke said “some growers might be questioning whether they’re doing something wrong with fertiliser and water, but it’s actually earwigs. […] I’ve got blocks where 100 per cent of flowers and shoots have been eaten by earwigs.”
European earwigs typically live for about a year, hatching in early spring before moving to tree canopies.
They can also be found hiding in areas such as bark crevices, fruit clusters, curled leaves and inside tree guards.
Mr Altman and Dr Horne said control methods for European earwigs included using seed dressings, baits or insecticide sprays, and ensuring trunk guards weren’t buried into the soil at their bases. “Whilst there is no threshold for earwig control, it is likely that damage similar to the previous season will occur if numbers are not lowered,” they added.
“Therefore, detecting the first signs of activity helps to time any possible control actions.”
However, Mr Doecke said the number of sprays available to control the “emerging problem” was limited.
“You’ve got to check pretty carefully with your packing shed, and your reseller, as to what you can use,” he said.
This story was originally posted on abc.net.au and it was written by Eliza Berlage