Freed, Thomas Z.The success of an invasion can be mediated by biological interactions (e.g. competition and predation). The newly invasive mosquito <italic>Aedes japonicus</italic> has established in the range of the competitively superior resident mosquito <italic> Aedes albopictus </italic> and the predatory indigenous mosquito <italic>Toxorhynchites rutilus</italic>. I tested the hypotheses that intraspecific aggregation, fluctuating resources, or keystone predation are facilitating the invasion of <italic>A. japonicus</italic> into the range of <italic>A. albopictus</italic>. Populations of <italic>A. japonicus</italic> and <italic>A. albopictus</italic> were negatively correlated with each other and intraspecifically aggregated in field studies, suggesting that aggregation is facilitating coexistence. Resources showed a high amount of spatial variability, and <italic>A. japonicus</italic> populations were strongly associated with resource-rich containers, providing evidence for the fluctuating resource hypothesis. A laboratory experiment showed that predation suppresses <italic>A. japonicus</italic> populations to a greater extent than interspecific competition when all three species co-occur, and provided no evidence for keystone predation.ThesisEcologyBiologyEntomologyAggregationAsian Bush mosquitoAsian Tiger mosquitoCompetitionFluctuating ResourcesKeystone predation