THEY are the bane of the home vegetable grower and they deliver a nasty bite, but are earwigs all bad?
That was the question posed by CSIRO researcher Matthew Binns at a recent Grains Research and Development Corporation (GRDC) update.
He said farmers did not want to have earwigs in autumn but by spring they were not a bad thing.
"In the autumn they can cause significant damage to broadleaf crops, especially canola, lucerne and lupins," Dr Binns said.
"However, by spring there is some evidence they could have a beneficial impact as they are a predator of pest species of aphids."
Dr Binns said little research had been done on earwigs over the years in spite of them being documented as sporadic pests of crop species for many years.
However, he said it appeared reports of damage had increased in recent years.
"There are more reports of damage, especially from Victoria, NSW, South Australia and southern Western Australia, but we are not yet sure why, we are looking into whether it is related to time of sowing or different planting systems but there is no answer as yet."
Dr Binns said there were at least 80 different species of earwigs in Australia, with indications that European earwigs were the most damaging.
However, he said there had never been definitive research into how big their benefits were in the spring time as aphid predators.
"It really is a difficult one to weigh up, the first thing we would encourage if you are seeing that damage in autumn is to make sure you've identified the correct species," he said.
"Most are not associated with crop damage so before considering control you need to make sure it is the earwigs causing the problem."
He said his research was looking at the life cycle of the earwig and how that impacted on the timing of crop damage.
"Generally canola is planted and emerged several weeks before the European earwig juveniles hatch, which means the crop avoids the severe damage you can see with the juveniles.
"However, adults will be present when the crop emerges and they can also cause damage, although there is a window where the female is underground with her eggs and not feeding."
In terms of insecticide efficacy should a farmer think chemical control was necessary, Dr Binns said the research had showed fipronil was far more effective than imidacloprid.