Knowledge of bollworm feeding behavior in response to cultivars is critical to understanding HPR, investigating basic insect-plant relationships, developing economic injury levels and designing computer modeling of pest-plant systems. We conducted an intensive greenhouse study of the behavior of Heliothis zea larvae on susceptible and resistant cultivars. The cultivars utilized were Stoneville-213 glanded (STV-213GL) and glandless (SIV-213gl) isolines and Tamcot CAMD-E. Using 1st, 3rd and 5th instars and two conditioning treatments, the following components were recorded: The frequency of behavioral activities and occurrence on various plant parts during a 10 hr. period. Differences in behavior on the three cultivars will be discussed.