The invasive container-dwelling mosquito Aedes albopictus (Skuse) shows modest behavioral responses to water-borne cues from predatory Corethrella appendiculata Grabham in North America. We investigate whether Ae. albopictus adjust their antipredatory responses to be proportional to size-dependent risk of predation. Fourth-instar Ae. albopictus attain a size refuge from C. appendiculata predation, and we compared the responses of second- and fourth-instar Ae. albopictus to cues from C. appendiculata predation. More vulnerable second-instar larvae showed a larger change in behavior in response to predation cues than did less vulnerable fourth-instar larvae, indicating threat-sensitive behavioral responses by Ae. albopictus.