To investigate the possible role of landscape connectivity on the genetic structure of isolated populations, we examined the effects of habitat corridors on the population genetics of a vagile butterfly species, Junonia coenia, within a large-scale, experimental system. Using allozyme electrophoresis, a total of nine loci were identified and scored, six of which exhibited polymorphism. Our data demonstrated consistently higher levels of expected (H_e) and observed (H_o) heterozygosity in butterflies sampled from patches connected by corridors compared to unconnected patches. A t-test comparing H_e and H₀ in connected versus unconnected patches found a marginally significant difference in one locus, the glycolytic enzyme phosphoglucose isomerase (PGI). Connected patches exhibited overall lower F_ST values compared to unconnected patches, indicating potentially increased levels of gene flow due to corridors. Our results support previous investigations on dispersal and population size for J. coenia, and show that higher dispersal through corridors promotes genetic variability at a locus (PGI) implicated in dispersal and fitness in butterflies.