This research investigated how the striped cucumber beetle, Acalymma vittatum (F.), responds to the presence of a predator, the wolf spider Rabidosa rabida (Walckenaer). We answered four questions. (1) Does a beetle alter its behavior in the presence of a wolf spider in a laboratory microcosm? (2) Do striped cucumber beetles in nature modify their behavior when a wolf spider is nearby? (3) If beetles do respond to the presence of a wolf spider, what types of cues do the beetles use to detect the predator? (4) Does the proximity of other beetles affect how beetles respond to the predator? In laboratory microcosms, the presence of a spider reduced the frequency at which beetles fed, but beetles did not change their feeding behavior in the presence of a nondangerous arthropod, the cricket Achaeta domestica. Field observations conducted at night in cucurbit gardens revealed that a spider within 15 cm of groups of beetles increased by ≈1.6-fold the rate at which beetles left the plant. The proportion emigrating was higher as group size increased, but group size did not affect the responsiveness to the predator. Further laboratory microcosm experiments revealed that the striped cucumber beetle consistently relies on tactile cues and sometimes on visual cues to detect the wolf spider. In one experiment, the presence of the wolf spider affected the feeding rate of a beetle when it was on the plant, but the most consistent behavioral response to the presence of the spider was to leave the plant at a higher rate.