Two species of Cecidomyiidae (Diptera) and their galls on stems of Verbesina alternifolia (L.) Britten ex Kearney (Asteraceae) are reexamined. Neolasioptera imprimata Gagné, new species, forms a slender, slightly tapered, woody gall. Neolasioptera verbesinae Möhn forms a much more conspicuous, ovate, relatively soft gall and is redescribed. Comparative notes on the biology of the two species are provided. Neolasioptera incisa Plakidas is a new synonym of N. verbesinae.
