Abstract: The external morphology of the compound eye of Hyphantria cunea, and the microstructure and its changes under different light intensity were observed by using a scanning electron microscopy and an optics microscope. The result showed that the compound eyes were hemispherical, and formed an upended typeface of the Chinese figure "eight" on the head. Male and female eyes have approximately 2 900 and 2 700 ommatidia. Each ommatidium was composed of dioptric apparatus, retinula cell column, the rhabdom and basement membrane. The dioptric apparatus and retinula cell column were surrounded by primary iris pigment cells and six secondary iris pigment cells, and pigment granules and a reflecting tracheal sheath were found in the basement membrane. Moreover, in light adaptation, most of pigment granules of secondary iris pigment cells gradually invaded the clear-zone from the cone region and evenly distributed in the whole region between the cones and the clear-zone. When the eye was in dark adaptation, the pigment granules of secondary iris pigment cells withdrew back to the cones and distributed around the crystalline cone. However, the microstructures of male and female compound eyes were not different under the same light- or dark-adaptation. In conclusion, the compound eye of H. cunea belonged to a refracting superposition eye. In light- or dark-adaptation, it could adapt to the change of ambience light intensity by controlling the longitudinal movement of pigment granules.

Key words: Hyphantria cunea compound eye, light /dark adaptation, external morphology, microstructure