These derivatives include ethyl methacrylate (EMA), butyl methacrylate (BMA) and 2-ethyl hexyl methacrylate (2-EHMA). Hexyl acetate is an ester with the molecular formula CHO. The ubiquitous "green apple" aroma is based on hexyl acetate. In blue light cystoscopy hexyl aminolevulinate hydrochloride is instilling a photosensitizing agent, into the bladder. Hexyl aminolevulinate hydrochloride for diagnosis of bladder cancer. Males are attracted to the queens via olfactory signals composed of hexyl hexanoate.