Laboratory experiments were used to determine what factors might affect predation on larvae ofGlyptotendipesspp. (Diptera: Chironomidae) byGambusia holbrooki(Baird and Girard). Tube presence, tube construction material, prey size, and habitat heterogeneity were examined as factors influencing predation. Tube presence significantly reduced predation byG. holbrooki, and large larvae were preyed on significantly more often than were small larvae. Predation was not significantly affected by differing levels of habitat heterogeneity.