An Oriental fruit fly.

An Oriental fruit fly. (Courtesy California Department of Food and Agriculture / July 10, 2012)

Oriental fruit flies have been detected in Laguna Beach, and the state will begin a treatment program this week, according to the California Department of Food and Agriculture.

Two flies were found between July 2 and July 5 in the city, within half a mile of each other, according to a news release. Due to the timing and location, the state believes there is an infestation in the area.

The Oriental fruit fly, somewhat larger than a housefly and yellow in color with a "T" marking, is considered a serious pest in Southeast Asia, the Pacific Islands and Hawaii.

According to a CDFA document, exotic fruit flies have cost Hawaii's local produce more than $300 million a year.

The female fly lays its eggs under the skin of fruit, rendering it unsuitable for eating. The CDFA said California crops such as citrus, dates, avocados, tomatoes and peppers could be in jeopardy.

If the fly became established in California, the state estimates a potential loss of $44 million to $176 million in damages to crops. The state could also face quarantine restrictions by the U. S. Department of Agriculture and international trade partners, a CDFA document said.

The "male attractant" treatment will be used, which will cover the 7.5 square miles surrounding the detection areas. The treatment consists of mixing attractant with pesticide, which lures male flies and kills them, the release said. The method has been used since the 1970s in the state.

CDFA said that the most common reason for infestation is "hitchhiking" — when travelers bring back produce from foreign countries that are infested by the flies.

"The key is to move quickly and take action before the pests can cause widespread damage," CDFA Secretary Karen Ross said in a statement.

For more information about the pesticide, spinosad and the treatment process, visit the CDFA website.

joanna.clay@latimes.com

Twitter: @joannaclay