DNA sequence studies revealed two additional species of Neodiprion in eastern United States, and morphological studies support their recognition. One, which is sympatric with and morphologically similar to Neodiprion abbotii (Leach) in southeastern United States, is recognized as Neodiprion fabricii (Leach), revised status. The larvae feed on Pinus taeda L. and P. echinata Miller. The other, described as Neodiprion knereri Linnen and Smith, n. sp., on Pinus clausa (Chapm. ex Englem.) in Florida, is close to Neodiprion virginiana Rohwer.