NEW England farmers are turning a "blind eye" to smooth bottoms that could rid rams of flystrike.
Instead, many flocks are running around with wrinkly bottoms that are a magnet to blowies.
These are the findings of a team of CSIRO scientists based in Armidale.
They have found selectively breeding sheep for smoother bottoms has helped in the fight against flystrike and is an alternative to mulesing.
"It's not complicated technology," CSIRO animal health team leader Peter Hunt said.
"All you have to do is look at a ram's bottom and give them a score for breech wrinkle with your eyes."
Flystrike is a health and welfare risk to sheep and costs $28 million in losses annually.
Blowflies lay their eggs on the animal and when these turn into maggots they eat the sheep's flesh.
Research conducted in Armidale and Western Australia found the flies preferred wrinkly areas on the sheep to lay their eggs.
So the team at CSIRO developed a breech wrinkle score, from one to five, for producers to test how wrinkly their sheeps' bottoms were. A score of one is for a relatively wrinkle-free backside, with five showing many folds and wrinkles.
Once the woolgrower has examined the animal's backside for wrinkles, they could selectively breed smoother-bottomed Merinos for future protection against flystrike.
"We have known about this for the past decade, however, farmers seem to be slow on the uptake," Dr Hunt said.
Best time to look for wrinkles, or folds, in bottoms is in spring, just before shearing. The blowfly larvae is most active between 26 degrees and 38 degrees.
"There are many options that will help you reduce your risk of flystrike," Dr Hunt said.
He and other scientists are puzzled why more farmers have not picked up on the breech wrinkle score, which is free and easy to conduct in smaller flocks, such as those in New England.
"Genetic options are long term and permanent, making them a valuable tool in lowering your risk."
The CSIRO scientists are also developing a flystrike vaccine, with initial results showing they can produce high antibody levels in sheep against the blowfly.
Their results were delivered at an open day, held at CSIRO's Armidale campus, on Wednesday, November 15.
More than 100 guests, farmers, industry representatives and scientists attended the day, Celebrating Country, Community and Agriculture, aimed at showcasing the organisation's current research.