The introduction of exotic and invasive species into novel habitats poses one of the greatest threats to biodiversity worldwide. There has been considerable interest in the effects of exotic forest insects and diseases on their native hosts. In addition to these direct effects, the cascade of indirect effects that extend beyond the primary host to the associated native biotic communities should also be considered. A range of widely researched non-indigenous species were reviewed for information on these indirect effects. In particular, the extent to which exotic species affect native insects, both terrestrial and aquatic, were considered. As the rate of introduction of exotic species is likely to increase in the future, it is useful to examine current introductions in terms of both direct and indirect impacts on native forest communities. This will allow us to predict and perhaps mitigate some of the effects of introductions in the future.