Our knowledge of the main determinants of invasion success is still incomplete. Among these factors, the effects of biological traits, including fecundity, longevity and dispersal in newly colonised regions, are pivotal. However, while numerous studies have considered ecological and evolutionary impacts of non-native species, their biology often remains understudied. Despite the continuous geographic expansion of Merizodus soledadinus (Coleoptera: Carabidae) at the Kerguelen Islands over recent decades, the main life-history parameters of this species are unknown. We determined adult longevity under controlled conditions, monitored seasonal activity through pitfall trappings, and analysed temporal variations of egg load and body reserves in field-collected individuals. Themedian adult life span (LT50) was 241 days, with maximum longevity of 710 days (N = 500). Females carriedeggs throughout the year (8.94 ± 3.56 eggs per female), and it was not possible to pinpoint any clear egg-layingperiod. Year-round trappings demonstrated continuous activity of adults over seasons, with a peak during the austral summer that may arguably be associated with higher temperatures. Body stores (glycogen and proteins) did not vary significantly through the year, suggesting that adults feed continuously despite different prey availability between summer and winter, possibly via diet shifts. The amount of triglycerides increased at onset of summer, which may be associated with higher summer locomotor activity and/or more intense predation and reproduction.