Residents of Perth and south-west WA have been bothered by fewer flies this summer. Scientists say it is all thanks to the humble dung beetle and mild weather in spring.

Rob Emery, a senior entomologist with the Department of Agriculture, told 720 ABC Perth that anecdotally, there had been many fewer flies in the south-west of WA in the recent months.

"The bush flies are a native insect that live out in the far eastern wheatbelt. As summer approaches we get easterly winds and that pushes the flies into the south-west, where they concentrate.

"Once the dung beetles become active over summer, they will start burying the dung before the flies can breed in it.

"If the flies arrive early, before the dung beetles are active, then the flies drive us nuts.

"Last November it was a little cooler than previous years so the flies just didn't get pushed into the south-west then.

"The summer dung beetles are out there now shredding the dung as fast as they can."

The humble dung beetle provides 'biological control'

Mr Emery said the work done by the CSIRO to introduce more dung beetles in the 1970s and 80s has greatly reduced the bushfly numbers in summer.

The Department of Agriculture, in partnership with the CSIRO, commenced an additional dung beetle program in 2011 to focus on springtime.

"We have released two new species of dung beetle that will hopefully be active over spring and bury the dung as soon as the flies arrive in November," he said.

"They also recycle nutrients into the soil, and generally do a fantastic job."