(A) Histochemical image of the uneverted cornua gland of a 3-day-old drone. Farrats Gum with ethyl gallate is used to detect lipids. (B) Histochemical image of the uneverted cornua gland of a 12-day-old drone. The Oil Red O solution used is 0.5% in 100% propylene glycol to detect lipids. CtI, cuticle with indentations; CtS, smooth cuticle; S, secretion; Sr, secretion which colored red after staining.