Establishment of red imported fire ants in California could cost the state's urban residents $257,771,386 annually, according to a conservative estimate by Jay Hamilton, a UC Riverside graduate student, given at a recent UC Agricultural Issues Center conference on exotic pests.

Red imported fire ant queen being tended by workers.

A native of South America and established in many parts of the southern United States, the aggressive pest was detected in the San Joaquin Valley in 1997 and is now found in Fresno, Kern, Orange, Los Angeles, Riverside and San Diego counties. Hamilton calculated the ant's nearly $258 million price tag by studying a survey on its costs conducted by Arkansas officials. The estimate includes only costs of pesticides, replacement of damaged electrical equipment and medical treatment, not significant potential agricultural and ecological expenses.

Hamilton said his figures, and the nuisance caused by the pest, underscore the urgency to eradicate red imported fire ant rapidly and completely from the state.