Florida agricultural officials today declared an end to a 3{-month Medfly infestation with a slap at California for taking so long to get rid of its pests. Helicopters sprayed up to 20 square miles of suburban Miami with malathion in eight aerial treatments to kill Mediterranean fruit flies, considered the most destructive farm pest because it can attack 250 fruits and vegetables. California's year-old infestation has spread to more than 900 square miles with limited aerial pesticide spraying at a cost of more than $38 million, said Florida Agriculture Commissioner Doyle Conner. ``It is absolutely vital to move quickly and aggressively, which is exactly what we did,'' he said. Florida's $1.6 million eradication effort began after a fly was trapped near Miami International Airport on April 16. By May 21, 23 Medflies were found at 21 locations. ``The bottom line is that we've turned back a serious threat to our food supply in an environmentally sound program involving a limited geographic area,'' Conner said. Unlike California, where malathion spraying produced a public outcry, the spraying in Virginia Gardens, Miami Springs and parts of Hialeah went on with little fuss.