The New World species of Chaenusa Haliday sensu lato are revised, and a diagnosis is provided for Chaenusa s.l. Four new species from North America, Chaenusa trumani Kula, Chaenusa virgili Kula, Chaenusa whartoni Kula, and Chaenusa woolleyi Kula, and two new species from South America, Chaenusa hirsutissima Kula and Chaenusa ireneae Kula, are described. Chaenusa americana (Riegel), new combination and Chaenusa saxicola (Riegel), new combination are transferred from Chorebidea Viereck. Chaenusa bergi (Riegel), revised combination is returned from Chorebidella Riegel. Chorebidea bessae Riegel is a new synonym of Cha. americana, and Chorebidea mcclurei Riegel is a new synonym of Cha. saxicola. Chaenusa anticostae Riegel and Chaenusa illinae Riegel are new synonyms of Chaenusa quadriceps (Ashmead). Chaenusa americana, Cha. bergi, Chaenusa californica Riegel, Cha. quadriceps, Chaenusa rossi Riegel, and Cha. saxicola are redescribed. Host and spatiotemporal distribution data are provided, including new host and distribution records. The status of several holotypes is discussed, and a key to the New World species of Chaenusa s.l. is provided.