A native of the Mediterranean area, olive fruit fly is considered the most damaging pest of olives in southern Europe, North Africa, and the Middle East. The olive fruit fly was first observed in North America infesting olive fruits on landscape trees in Los Angeles County, in October 1998. Detection surveys through May 2000 showed olive fly generally infesting coastal areas from San Luis Obispo south to San Diego and into Baja California as far south as San Vicente. State and Federal regulatory officials have concluded that it is not possible to eradicate olive fly from California. There is considerable potential for spread and damage to the commercial California table and olive oil industries of the San Joaquin and Sacramento valleys and coastal growing districts.
Olives grown by homeowners for home curing or oil are equally at risk.
Once established, multiple insecticide applications are likely to be required to prevent extensive fruit damage by olive fly. Overwintered adult flies lay eggs in mature, unharvested olive fruits in late winter and spring. Female flies from this generation then attack the new crop olives as they develop in July and August. It is believed that at least three, possibly four, generations of olive fruit flies could develop in various areas of California. In southern areas such as San Diego County, development may be continuous throughout the year.