The spread of exotic mosquito species into new environments can introduce shifts in mosquito populations and potentially alter public health risks to mosquito-borne diseases. The successful establishment of exotic species may occur due to their competitive advantage over other cohabitating species. We hypothesized that the recently introduced exotic mosquito Aedes japonicus japonicus (Theobald) would be a more effective competitor than Aedes atropalpus (Coquillett) and Aedes triseriatus (Say), and an equal competitor to Culex pipiens (L.) based on larval abundance data within tire habitats. Impacts of competition were measured using the larval developmental rate and survival of larvae, adult mortality, wing length, and sex ratio. We found that intraspecific competition acted strongest against Ae. japonicus versus the other three resident mosquito species by delaying larval development and increasing adult mortality. Interspecific competition was generally weak and significant main effects were only detected for species and density. Overall, our results show that larval competition between Ae. japonicus and the three resident species was weak when present, indicating that other ecological or behavioral factors may be influencing the invasion success for Ae. japonicus in North America.