Twenty one species of gall forming midges in the genus Celticecis Gagné 1983 have been reported in North America, but there is limited information regarding the northeastern range of these species. To gain a greater understanding of the range of these cecidomyiids, hackberries (Celtis spp.) were surveyed for galls formed by Celticecis spp. at selected sites in south central and eastern Pennsylvania, northwestern New Jersey, southeastern New York state, and at one site in southeastern Connecticut. Galls were identified by morphology, and the species of gall formers were confirmed by considering the morphology of third instar larval sternal spatulas. Hackberry galls formed by ten Celticecis species were found to occur in Pennsylvania, with nine representing new state records. Hackberry galls formed by nine Celticecis species were found in New Jersey, with all nine representing new state records. Hackberry galls formed by five species of Celticecis were identified in southeastern New York, with four representing new state records, and galls of one Celticecis species were found at a site in southeastern Connecticut, representing a new state record for this species. This study expands the northeastern range of a large number of gall forming midges of the genus Celticecis in northeastern North America.