Steve Lyle with the state Department of Food and Agriculture says that’s the first sign of a possible medfly infestation. He says the pest can infest more than 260 kinds of fruits and vegetables and cause between $1.3 and $1.8 billion in annual losses to agriculture.   

"That’s a pretty extensive bite out of the food supply and a key reason why we move as quickly as we do to try to erradicate the infestation."

Lyle says blanketing an affected area with sterile male flies gradually wipes out the population because female flies die after mating.