The Mexican fruit fly, eradicated in California after a $2.7-million malathion spraying battle last year, may be preparing a comeback. State agriculture officials slapped a ban on imported Mexican mangoes last week after fruit fly maggots were found in a Yuba City supermarket, said Bill Edwards, Los Angeles deputy director of agriculture. More larvae were found in Orange County this week. The infested fruit was removed from the stores and destroyed, but the ban on imported mangoes will remain in effect until federal and state agriculture authorities can certify that Mexico is properly fumigating its mango crops, Edwards said. Consumers are requested to check any mangoes they have purchased and report any evidence of larvae or damage to agriculture officials.