Three more Mediterranean fruit flies have been found in Escondido, Calif., leading officials to expand a quarantine area that includes significant avocado and citrus acreage.

Two active males and one female were found in December in southwestern Escondido, said Bob Atkins, agricultural commissioner of San Diego County. As a result, an additional 30-40 square miles will likely be added to an 81-square-mile quarantined area in the region, he said.

The quarantine was first established in September, when a mated female Medfly was found in Escondido.

With pre-harvest treatments, avocado and citrus trees shouldn’t be affected, Atkins said.  But with growers already facing high water costs, the extra input cost could be a burden, Atkins said.

“It will be a little more expensive, but at least they’re not going to lose fruit,” he said.

Medfly infestations can cause severe losses in more than 260 types of fruits and vegetables.