Developmental Changes in the Interference Reflectors and Colorations of Tiger Beetles (Cicindela)

SUMMARY Samples of cicindelid cuticle were examined at various stages of adult ecdysis. The multilayered potential reflector was secreted in the initial stages of the moult, verifying that it is not tectocuticle and supporting the contention that it is a form of inner epicuticle. At early stages of ecdysis, the electron-dense layers were visible only when the section was post-stained. During post-ecdysial colour development, the dense layer increased in inherent electron density. Concurrently, the reflector increased in refractive index and the interference coloration increased in intensity and wavelength of maximum reflectance. Black pigment was also deposited simultaneously within the outer portion of the cuticle. It is proposed that electron-dense material was deposited in situ within the inner epicuticle after ecdysis, thereby increasing the wavelength and reflectance of interference colour.