The appearance of the Mediterranean fruit fly (medfly) and other tephritid-type fruit flies in general have become so commonplace that the insects are essentially a fact of life for most Californians, particularly in the Bay Area, the Los Angeles Basin, and the greater San Diego region.

Originally from central Africa, the medfly is now distributed throughout that continent, the Mediterranean regions of Europe, South and Central America, Hawaii, and western Australia with intermittent appearances in Florida and near-continuous discoveries in California.

With the exception of the Florida finds and a small outbreak in Brownsville, Texas, in 1966, this pest has never been detected in other states with medfly-friendly climates.

The medfly is a serious threat to California agriculture since the insect lays eggs in mature, market-ready fruits and vegetables. The eggs hatch and the maggots destroy the host.

Medfly hosts exceed 250 crops including stone and pome fruit, citrus, avocado, plum, walnut, tomato, pepper, and persimmon. According to the California Department of Food and Agriculture, the combined value of medfly hosts in California is nearly $10 billion.

Since 1982, about 250 emergency projects on tephritids have been conducted including more than 60 for the medfly and 150 projects for the oriental fruit fly. In 2009 and 2010, a total of 123 tephritid adults were captured, representing nine species in 11 counties that triggered 59 delimitation (trapping) and 16 eradication programs.

Although medfly discoveries and the intervention programs that follow are a nuisance for urban dwellers in the quarantine zones, the insect can be devastating for the hundreds of commercial growers located within five miles of a tephritid outbreak.

For these growers, medfly/tephritid finds that typically first occur from July to October can have catastrophic economic consequences with quarantines typically lasting until early summer of the following year. Like an unexpected lightning bolt, these medfly finds can instantly place at risk the livelihoods of hundreds of growers, packers, and distributers.

In 2009, a Fallbrook, Calif., grower estimated the loss on two acres of avocados at about $14,000. Restrictions due to the 2007 medfly quarantine in Dixon, Calif., located in Solano County in the Sacramento Valley, reduced the numbers of tomatoes in tubs on harvest trucks from 20 percent to 33 percent. Quarantine restrictions prevented growers from traditionally mounding the tomatoes and the availability of tarp to cover the tomatoes was limited which caused crop loss.

A farmer in the Dixon area who sells produce by the box to 800 urban customers had to reduce his price in half since it was illegal to ship produce included on the list of 260 medfly hosts.

In 2009, some growers in Fallbrook, Calif., were faced with overlapping pest quarantines for the medfly and the Asian citrus psyllid which included different regulatory requirements on treatments, durations, and costs.