Experiments were conducted in an environmental growth chamber to determine the movement and feeding preferences of Nezara viridula (L.) and Euschistus servus (Say) on individual cotton plants. Fifth instars were caged by species on a single cotton plant (FM 9063 B2F) containing four discrete boll sizes ranging from 1.1 to 3.0 cm in diameter over a period of 5 d per replication. Two digital video cameras were simultaneously focused on each of the four bolls per plant to visually confirm stink bug resting and movement. During the study, a total of 4,080 h of video footage was recorded and analyzed. Results showed that N. viridula and E. servus did not prefer the exact same boll sizes. In a trial with eight stink bugs per plant, N. viridula spent more time on the three larger boll classes, 1.6–2.0, 2.1–2.5, and 2.6–3.0 cm. In a separate trial with one stink bug per plant, N. viridula spent more time on the larger boll classes while E. servus exhibited the strongest preference for 1.1–1.5 and 2.1–2.5 cm bolls. N. viridula moved more often than E. servus and both species moved more often during photophase compared with scotophase. Regardless of species or number of bugs released, bolls in the smallest boll size class fell off the plant about 3 d after the bugs were released. These results confirm that scouts who are estimating stink bug damage should select bolls in the 2.1–2.5 cm diameter boll size class.