Wax, 85% of which consists of orthorhombic crystals, has been found in the cocoon of the hornet Vespa analis Fabricius by means of high-resolution (13)C solid-state nuclear magnetic resonance (NMR). GC-MS analysis revealed the major components of the wax in the cocoon were linear alkenes and alkanes with a total of 23 or 34 carbon atoms. At 40.7 degrees C a DSC absorption peak and a (13)C NMR chemical shift change were observed and interpreted as the result of a crystal transition from the orthorhombic to rotator phase of the wax molecules. At 55.5 degrees C melting of the wax was observed. The amount of crystalline wax deposition varied with the part of the cocoon-crystalline wax was concentrated in the silk sleeve lining the inner wall of each comb cell but there was very little in the silk cap projecting from the end of each cell. Because the wax components of the larval cocoon were almost identical to those of the larval cuticle, despite a slight difference in the profiles, they might have come from the larval cuticle via direct body contact with the cocoon.