Pulvinariella mesembryanthemi(Vallot) andPulvinaria delottoiGill are closely related soft scales recently introduced to California, where they attack aizoaceous ground covers. Populations of both species were cultured onCarpobrotus edulis(L.) ×aequalateris(Haw.) under greenhouse conditions to determine their responses to various fertilizer formulations and concentrations and five water regimes. We measured scale growth, survivorship, ovisac size, fecundity, and developmental time for each treatment population. There were no differences in population responses ofP. delottoito any water or fertilizer regime. Although all fertilizer treatments increased growth rate ofP. mesembryanthemi, we found no significant correlation between amount or form of nitrogen addition and survivorship, ovisac size, or fecundity. Survivorship was similar amongP. mesembryanthemipopulations treated with different water regimes. However, as watering frequency increased,P. mesembryanthemigrew faster, ovisacs were larger, fecundity was greater, and developmental time was shorter.