The prey-capture behavior of the juveniles of Evarcha culicivora, an East African mosquito-eating jumping spider, was investigated in the laboratory using living prey and using dead, motionless lures made from two mosquito species, Anopheles gambiae sensu stricto and Culex quinquefasciatus. Having tested individuals of E. culicivora that had no prior experience with mosquitoes (rearing diet: only chaoborid and chironomid midges), our findings imply that the small, but not the large, individuals of E. culicivora have an innate predisposition to adopt Anopheles-specific prey-capture behavior. Findings from lure tests implicate posture as a primary cue by which the small juveniles of E. culicivora identify Anopheles. Each individual of E. culicivora was presented with lures, that were either in the posture typical of Anopheles or in the posture typical of Culex. Small, but not large, juveniles of E. culicivora often responded to Anopheles mounted in the Anopheles posture and Culex mounted in the Anopheles posture by taking an indirect route or a detour to the prey which enabled the salticid to approach the lure from behind. However, detours were not routine for small or for large individuals of E. culicivora when the lure, whether made from Anopheles or Culex, was in the Culex posture. When tested with live mosquitoes, small juveniles of E. culicivora were more effective at capturing Anopheles than Culex. Large juveniles were more effective than small E. culicivora juveniles at capturing Culex, but large and small juveniles had similar success at capturing Anopheles.