Green Life: Barmy army

Only their moms think they're pretty, but bats are the superheroes of pest control

If you were a false codling moth, you'd dig fruit. Your sole fixation would be to lay your kids in anything from peaches to pomelos, where they would worm themselves ever deeper into the fruit to feast on its mouthwatering flesh.

In this way, you and your mates would destroy fruit across the country and cost the industry at least R300-million a year. Farmers would hate your guts and spray their crops with pesticides, which would cost them a lot of money and inspire questionable environmental impacts.

But let's not forget you'd be a juicy morsel yourself, and that bats would love to eat you - which is why you'd have reason to shake in your little false codling moth boots right about now.

Launched in mid-2010, the Colors Fruit/Ecosolutions biological control project has installed 200 bat boxes, or artificial roosts, on 11 fruit farms in the Western and Eastern Cape as a greener way to control the problem insect.

Ecosolutions director Jonathan Haw, one of the leading brains behind the five-year trial project, believes the preliminary results are surprisingly encouraging.

He says 30% of the project's bat boxes have already attracted about 300 bats by recreating artificial crevices in areas where the animals' natural habitat - like dead trees removed by monoculture farming - has been destroyed.

The average box in the project can accommodate between 600 and 1000 bats - a potential biological air force of some 20000 miniature fighter jets per farm. Haw adds the rate at which the project's boxes are luring bats is defying expectations: "Every science paper we've read has advised a minimum of 18 months to expect occupancy, but 60 of our boxes have already been filled. That means we've hit the jackpot in terms of finding something that is palatable to bats."

Sounds romantic in a countrified sort of way - jettison pesticides in favour of enticing a charismatic but threatened nocturnal hunter back to the platteland, and use it to nuke crop pests. Yet many homeowners and farmers have opened up standard bat hotels only to find that these have been shunned by the intended patrons.

"So you've some guy who sticks up a box in his garage and no bats. But we're starting to understand there's a science to this - we've consolidated the best local and international designs into about four box types, which we've installed across our farms," Haw explains. Each box has been kitted out to take regular environmental readings which are analysed to create the ideal bat-box blueprint.

"We're starting to see trends," says Haw. "Our bats are showing a preference for boxes facing northwest, rather than east, for instance."

Bats respond to any insect eruption as a potential food source.

Sonja Brummer, a Kirkwood, Eastern Cape, fruit farmer participating in the project, hopes that the bat boxes will help improve her bottom line. "We're still waiting for the bats to move in, but I hope they'll help us harvest more fruit," she says.

Haw points out that bat boxes and pesticides can be used in concert. "We're not fans of pesticides, but some of our farms are still using them with bats. Use witchcraft if you must - just integrate everything in a way that also considers environmental options."

A participating Paarl fruit farmer who exports to Marks & Spencer in the UK, Ian Carstens believes bats will make his brand more likeable. "It's a nice story ... and can help with marketing," he says.

In the US, the economic contribution of bats is estimated at $3.7-billion a year. And, according to Haw, bats are incomparably cheaper than pesticides.

A 50ha fruit farm can spend around R200000 to R250000 annually on pesticides. But 20 bat boxes are likely to cost just R30000 a year.

"You're relying on an ally from nature that doesn't cost you much and allows you to export cleaner fruit," says Haw. "There's that expression, 'my enemy's enemies are my friends'. It's that simple."

• The Colors Fruit/Ecosolutions biological control project is funded by Colors Fruit. Visit www.colorsfruit.com or www.ecosolutions.co.za for contact details