Animals are said to have personality if they express consistent behavioral tendencies that consistently vary among individuals within the same population across time and contexts. The expression of personality may be subject to change across ontogeny and life history transitions; however, experimental studies addressing the ontogeny of personality are rare. Here, we evaluated the mean and repeatable trait expression in activity and space use across ontogeny and maturation in female and male predatory mites Neoseiulus longispinosus. The predators were individually kept on leaf discs with spider mites and pollen throughout development and maturation and their behavior was videotaped six times, each for 3 min, using a digital microscope. An automated video-tracking system, AnimalTA, was used to evaluate the activity and space use patterns of male and female predatory mites before and after maturation and mating. Activity was quantified by the proportion of time spent moving and space use by the proportion of time spent on the edge or in the center of the leaf disc. On average, adults were more active and ran faster than nymphs. Adult males spent more time moving at lower speed than adult females. Regardless of their sex, adults spent more time at the edge of the leaves than nymphs; movement along the edge increased over time in adult males but decreased in adult females. Females were repeatable in the proportion of time spent moving throughout ontogeny, but expressed different personality types before and after maturation. Males were not repeatable. Nymphs, regardless of their sex, were consistent in space use, but adults were not. Our study indicates that the expression and plasticity of predatory mite personality across ontogeny are contingent on the trait, life stage and sex in question.