Interspecific competition between two orb-weaving spiders,Metepeira grinnelli(Coolidge) andCyclosa turbinata(Walckenaer), was investigated by selective removal of the predators. The estimated predation rate of small prey was higher whereCyclosawas alone than where both species were present, because whenMetepeirawas removed the density ofCyclosabecame higher than the combined density ofMetepeiraandCyclosawhere both species were present and because the consumption rate of small prey byMetepeirawas very low compared with that ofCyclosa.The study suggests that, in some circumstances, a subset of predator species could be more effective in reducing prey populations than the entire natural guild.