Specimens of a population of Sarraceniopus nipponensis collected from Sarracenia alata in Louisiana, USA, slightly differ morphologically from specimens of the type location in Japan. Hence, a subspecies level for the USA-population is proposed. Ecological and behavioral data of S. nipponensis (Louisiana, USA) were collected. The development from larva to adult, skipping the facultative deutonymphal stage, takes about 6 days at an average temperature of 24°C (room temperature). Adults show a sex ratio of 1 : 2.6 in favor of females. Deutonymphs have a partially reduced sucker plate, apparently dispersing through ambulatory activity rather than phoresy. Precopulatory mate guarding occurs many hours before tritonymphs enter quiescence. During mate guarding, males rest motionlessly on the tritonymphal dorsum, but are not unable to move meanwhile. Legs I are conspicuously thick and serve as ‘safeguard holder’ while legs II are used to fight against male competitors and to hold on to the female regardless of environmental disturbances. The precopulated tritonymph is held in position directly beneath the male.