Total extracts from worker larvae, pupae, and adults of the honey bee were analyzed for their juvenile hormone contents. Using the 10-(heptafluorobutyrate)-11-methoxy derivative, the hormone was isolated in yields of 20 - 50% in nanogram quantities as calculated from isotope dilution and from gas chromatography with electron capture detection. The procedure is sensitive enough to isolate the juvenile hormone out of 1-4 grams insect material for qualitative and quantitative analysis. Only juvenile hormone 3 (methyl 10.11-epoxy-2-trans, 6-trans-farnesoate) could be detected as the predominant hormone homolog of all the three developmental stages. Juvenile hormone 1 (methyl 3.11-dimethyl-10.11-as-epoxy-7-ethyl-2-trans, 6-trans-tridecadienoate) could, if at all, only be identified in trace amounts, and juvenile hormone 2 was completely absent in all stages. This first systematic analysis of a hymenopteran insect shows a modulation of JH3 titre between zero and 2 ng per gram body weight during imaginal development and a rather constant JH3 titre near 10 ng per gram in the adult.