-Pollen is the natural source of protein for bees and it is commonly assumed that a high protein content in pollen is beneficial. Investigation of the optimal nutrient ratio for honeybees was prompted by our earlier study showing surprisingly high mortality in caged honeybees fed with the protein-rich pollen of Aloe greatheadii var davyana, although field bees experience optimal growth when feeding on this pollen. We tested the effect of different protein sources and different protein:carbohydrate (P:C) ratios on the survival and ovarian activation of caged bees. Bees fed casein showed consistently higher survival than those fed royal jelly or aloe pollen, regardless of P:C ratios. They survived longer on lower P:C ratios and longest on a pure carbohydrate diet. The greatest ovarian activation was recorded for bees fed royal jelly in a 1:3 P:C ratio, showing the superior quality of royal jelly for supporting development.Aloe / macronutrients / pollen / casein / royal jelly