This paper reviews the tribe Melolonthini (Scarabaeidae, Melolonthinae) in the southeastern United States, primarily in the states of Mississippi, Alabama, Georgia, and northern Florida. Four new species are described: Gronocarus inornatus, Hypothyce burnei, Polyphylla donaldsoni, and Polyphylla woodruffi. One new synonymy is made: Gronocarus multispinosus Howden is synonymized under Gronocarus autumnalis Schaeffer. Description of the previously unknown female is made for Polyphylla brownae Young. New collection records are presented for many species. Comments on natural histories and a key to species (omitting only species of the genus Phyllophaga Harris) in this region are presented.