Invasive species can have ecosystem effects that span aquatic-terrestrial boundaries.  We investigated the effects of an invasive riparian tree, Russian olive (Eleagnus angustifolia), on invertebrate diversity, biomass and production in a desert spring stream, Deep Creek, Idaho.  Invertebrates were studied at multiple reaches of Deep Creek in the 1970s.  One reach has since been invaded by Russian olive, setting the stage for a unique before-after-control-invasion comparison.  We hypothesized that diversity, biomass and production of invertebrates is negatively affected by Russian olive invasion due to a shift in basal food web resources from abundant autochthonous materials to a mix of autochthonous and poor quality allochthonous matter.  Russian olive presence has increased allochthonous inputs by two orders of magnitude and increased canopy cover from zero to fifty percent but has not caused a significant decrease in periphyton standing stock.  While diversity, biomass, and secondary production remained relatively unchanged at an uninvaded site, all decreased at the invaded site.  For example, we observed a decrease in overall biomass and a large decrease in the abundance of the grazer Optioservus.  Shifts in invertebrate community structure and productivity are important facets of ecosystem response to this riparian invasion.