California and federal agriculture officials have confirmed a Mexican fruit fly infestation near Azusa in Los Angeles County, Calif., prompting the declaration of a 70-square-mile quarantine.

The Mexican fruit fly is native to southern and central Mexico. The fly attacks over 40 different kinds of fruits and vegetables. Mexican fruit fly eggs hatch into maggots which tunnel through the fruit and make it unfit for human consumption.

At least 6.5 million sterile Mexican fruit flies were scheduled for release weekly over a 13-square-mile area at the core of the quarantine zone beginning Dec. 22.

Sterile fly releases have been used to eradicate fruit fly infestations in California since the technique was developed in the 1980s. Sterile Mediterranean fruit fly releases also occur throughout the year in the Los Angeles basin in order to combat repeated infestations by that pest.

Upon detecting a mated female Mexican fruit fly in a trap on Dec. 8, the California Department of Food and Agriculture (CDFA) and USDA expanded insect trapping in the area to detect additional flies. The effort has produced three additional wild flies, confirming the existence of an active infestation.

“As a farmer, I know this quarantine will be a hardship to growers in this area,” said CDFA Secretary A.G. Kawamura. “But I also know they understand that this is a necessary step to halt a major pest, and I want to thank them for their cooperation with this eradication effort.”

The quarantine regulates agricultural shipments from the quarantine zone to prevent movement of potentially infested commodities. Locally grown crops such as citrus and avocadoes will be inspected and may be treated, except for the Haas variety, which is thick-skinned and not a suitable host for this pest.

Crews are working with local growers, packing houses, transporters, farmers’ markets, and other related facilities to ensure compliance with the quarantine regulations.

In addition, residents and people moving through the quarantine zone are urged not to remove fruits and vegetables from the area. The quarantine requires that local residents not move home-grown fruits and vegetables from the property of origin. Residents may consume fruits and vegetables on-site or dispose of them by double-bagging them and placing the bags in the garbage.

The most common cause of these infestations is travelers who illegally transport prohibited plants and infested produce into the region.