A 70 square-mile quarantine area has been established around the Los Angeles suburb of Azusa following the discovery of a single trapped female Mexican fruit fly, with the California Department of Food and agriculture preparing to control the infestation.

After a further three fruit flies were discovered following the initial finding on 8 December, the body is has moved to prepare the release of 6.5m sterile fruit flies across the quarantined zone.

'We are geared up and have a good supply of sterile fruit flies ready for release,' Steve Lyle, director of public affairs for the state agency, told The Packer. 'We're ready to go.'

Mr Lyle confirmed that there were no significant commercial crops in the immediate area, and that the group was well drilled in fruit fly control following previous incidents involving the pest in a number of different guises including Mexican, Mediterranean, oriental and guava fruit flies.