Populations ofEurosta solidaginisFitch andEpiblema scudderiana(Clemens) attacking ramets ofSolidago altissimaL. were sampled in 1991 and 1992 on road margins (10 and 60 m from the road edge)in the Ottawa metropolitan area to investigate the effects of roadside conditions on the performance of gall-forming insects and their host plants. The growth ofS. altissimawas reduced near the road throughout the growing season in 1992 and similar trends were observed in 1991. However, the biomass of gall-inhabiting larvae and gall size did not differ significantly or consistently between the two distances from the road edge. Similarly, larval survivorship and mortality agents of gall-formers and the proportion of goldenrod ramets attacked byE. solidaginisandE. scudderianawere unaffected by roadside conditions. Thus, road stress may affect the host plant, but it is probably not severe enough to affect gall-formers, which might be better adapted to harsh environments and better protected against stress-induced changes in the quality of their food plant, as opposed to other guilds of insect herbivores such as sucking insects.