In an attempt to develop more suitable oviposition media for Mansonia colonization, 6 aquatic plants and strofoam2 were offered as substrates to determine oviposition preferences by placing them in the same ovipot. Female Mansonia laid eggs on each, i.e.; Pistia stratiotes, Salvinia cucullata, Lemna minor, Alternanthera philoxeroides, Jussiaea repens, Eichornia crassipes and styrofoam. The oviposition percentages were 50.2,23.6,22.2,1.3,0.9, 0.5 and 1.3, respectively,. Since the experiment indicated that the mosquitoes would oviposit in the absence of living aquatic plants a new ovipot with sliced styrofoam floating on the surface of tap water in a small plastic jar was prepared. Since our results were similar to those obtained using Wharton's ovipot, this technique is now routinely used in our laboratory for the oviposition of Mansonia uniformis, Ma. indiana and Ma. annulifera.