Monarch butterflies (Danaus plexippus) are famous principally for their spectacular annual migration up through North America. However, the subspecies D. plexippus megalippe, which resides mostly in Central and South America, does not show migratory behavior. We are interested in comparing these migratory and non-migratory relatives to determine the extent of their genetic divergence, and to identify genes which may be involved in the evolution of migratory behavior.