ESCONDIDO, Calif. -- A 77-square-mile quarantine is in effect in northern Escondido Wednesday following the discovery of a Mediterranean fruit fly, state agriculture authorities said.

Agriculture shipments from the quarantine zone are restricted to prevent the spread of the pest, and residents are urged not to remove potentially infested homegrown fruits and vegetables from the area, according to the California Department of Food and Agriculture.

The Medfly was discovered in a trap on Sept. 9. Since then, the CDFA has begun treating the area with a natural insecticide and started releasing hundreds of thousands of sterile Medflies in the quarantine zone in an effort to prevent the insects from producing offspring.

Medflies attack more than 260 types of fruit and vegetables. If left untreated, a permanent infestation could result in as much as $1.8 billion in annual agriculture losses, the CDFA said.

Quarantines are in place in Mira Mesa and Imperial Beach, where Medflies were also detected.