One of the most important factors limiting the use of coccinellid beetles in the biological control of certain insect pests is the difficulty experienced in rearing sufficient quantities. The standard method of rearing them on suitable hosts is often impracticable because of their restrictive diets. Such difficulties were encountered when the introduction of some coccinellid beetles was attempted in French Morocco, as a control measure for a coccid (Parlatoria blanchardi Targ.) on date trees. The problem of rearing or obtaining the host in sufficient quantity greatly hampered the production of the predators. For this reason, considerable time and effort was devoted to the development of a satisfactory and economic technique for the breeding of these predators on artificial media.