When locust cuticle is incubated together with N-acetyldopamine under aerobic conditions a compound is formed which is identical to one isolated in small amounts from naturally sclerotizedcuticles. The structure has been determined by mass spectrometry and NMR spectroscopy. It is 2-(3',4'-dihydroxyphenyl)-3-acetylamino-6 (or 7)-(N-acetyl-2-aminoethyl)-2,3-dihydro-1,4-benzodioxin.