Ampullae appear to be common in the larvae of some chrysomelid subfamilies. We describe and discuss the occurrence and use of these structures in larvae of Labidomera clivicollis (Kirby), on its host plant Asclepias verticillata L. (Asclepiadaceae) under field and lab conditions. Through film footage, we reveal that ventral ampullae are apparent on all ten segments of the larval abdomen; however, only those associated with segments AVIII–AX were actually used in ambulation by anchoring to the host plant. These ampullae always function with the true legs during movement. Our study unveils ambiguities in homology and terminology of abdominal ambulatory structures that are relevant to discussions of chrysomelid characters and phylogeny.