Novel host records and feeding behaviors are reported for five species in three genera of two cassidine beetle tribes, Hemisphaerotini and Imatidiini, from Ecuador. Carludovica Ruiz and Pav. (Cyclanthaceae) is reported as a new plant family and genus host for two species of Spaethiella Barber and Bridwell. Calathea G. Mey (Marantaceae) is reported as the first host record for Aslamidium capense (Herbst) and Calathea lutea Schult. and Calathea majestica (Linden) H. Kenn. are reported as the first host records for Aslamidium semicirculare (Olivier). Immature stages of Demotispa elaeicola (Aslam) are reported for the first time; larvae are external folivores and both larvae and pupae are solitary and lack exuvio-fecal shields. The adults and larvae of D. elaeicola feed by rasping palm fruits, a rare feeding pattern in Cassidinae.