Aptesis basizona (Grav.), a hymenopterous parasite of Diprion pini (L.), D. similis (Htg.), Neodiprion sertifer (Geoff.), and other Diprionidae in Europe, was Propagated for several years at Belleville, Ont., for release in biological control programs (Green, 1938), and for use as an experimental insect. It was observed that oviposition was reduced by lack of food and by change of food from raisins to a mixture of sugars and ager (Finlayson and Green, 1940). Fecundity of the females was greater when adults were fed on fresh, unpasteurized honey than on raisins (Finlayson and Finlayson, 1957). Both raisins and honey contain protein, in the proportion of about 8:1 (Anon., l945), so that it is unlikely to be a factor in the difference. As sugar content of raisins is about 73 per cent (Sun Maid Raisin Growers of California, in litt.) and of honey about 79 per cent (Watt and Merrill, 1950), it appeared that mineral trace elements or vitamins in the food might be responsible for the difference in the oviposition. Both raisins and honey contain potassium, chlorine, sulphur, calcium, phosphorus, sodium, magnesium, silica, iron, manganese, and copper, but the latter two are minor elements in raisins (Sun Maid Raisin Growers of California, in litt.; Apiculture Section, Entomology Research Institute, Ottawa, in litt.).