Abstract: The ultrastructure and function of male accessory glands of theblack cutworm Agrotis ypsilon (Rottemberg) were studied with light and electron microscopies and biochemical analysis. The results are summarized as follows: 1. The male accessory gland was a pair of tubules each divided into a pink base, an orange middle part and an opalescent terminal part. The morphological differentiation of the gland was completed during early pupal stage, but it performed full secretory function on the fourth day after emergence. 2. The gland cells were of secretory type with high capacity for protein synthesis. There were a lot of rough endoplasmic reticule and free ribosomes and numerous secretory vesicles in the cytoplasm.3. Apocrine and merocrine types, are suggested as the major secretory activities of these gland cells. The granules formed by apocrine secretion are glycoprotein in nuture, but the reticulate secretion formed by merocre activity is not glycopro tein. 4. The gland's secretions are species specific in the three species of noctuids,Agrotis ypsilon, Mythimna separala and Helicoverpa arrnigera. High temperature (32℃) inhibited gland's capacity to secrete proteins.

Key words: Agrotis ypslon, male accessory gland, ultrastrucrure