Satyrium favonius, the oak hairstreak or southern hairstreak, is a butterfly of the family Lycaenidae. It is found in the United States from southern New England and the Atlantic Coast south to peninsular Florida and west to central Illinois, south-eastern Colorado and the Gulf Coast.
The wingspan is 22âÂÂ38 mm.
The larvae feed on the leaves, buds and male catkins of Quercus species. The species overwinters as an egg.