This chapter reviews 2 studies using close-up video recording to seek behavioral indications of stylet penetration by aphids. Stylet penetration by wired apterous adult aphids was electronically monitored while simultaneously video recording the aphids’ movements on the plant. Cessation of body–antennal movements coincided with the start of electronic registration of stylet insertion, and renewed antennal waving–walking coincided with stylet withdrawal. The 2 assessments (electronic and video) of stylet penetration duration were significantly correlated with each other (with a 1:1 relationship) for both Aphis fabae Scopoli and Myzus persicae (Sulzer), suggesting that video recording of untethered aphids can be used to infer stylet penetration. Video assessment is particularly useful when observing behavioral effects, such as those of antifeedants, on unrestrained insects. A. fabae were given 15-min access to tick bean seedlings, and 4 stylet penetration parameters were assessed by video for each insect (time to 1st penetration, number of penetrations, duration of each penetration, and total duration of penetrations). Significant differences in all of these penetration parameters were detected between tethered and untethered aphids, and significant differences in time to 1st penetration and number of penetrations were detected between starved and nonstarved aphids. Treatment of seedlings with the plant-derived antifeedant polygodial did not affect any of these parameters. However, there were significant differences in all 4 parameters between aphids previously given 24-h exposure to polygodial-treated green paper, versus aphids exposed to solvent-treated green paper alone. The possible modes of action of polygodial are discussed.