Microsatellite and mitochondrial DNA (mtDNA) variability data were used to study outbreaks of Mediterranean fruit fly in California in the years 1992–94 and 1997–99. A total of 359 flies caught in monitoring traps during these years were examined at three polymorphic mtDNA restriction sites and two microsatellite loci. Composite genotypes obtained through analysis of these markers indicate at least five independent introductio...