Studies on the silk glands of Calpodes ethlius stoll, (Lepidoptera, hesperiidae)

Each silk gland of Calpodes ethlius consists of five distinct regions: the duct, the green, anterior, middle and posterior regions. Although the gland increases approximately tenfold in length during the larval life, the number of cells remains constant with a concomitant increase in ploidy which is not constant either throughout larval life or in the different regions of the gland. Histochemistry on the glands of the mid‐fifth instar larva shows that progressively more mucosubstances are deposited in the lumen, so that while in the distal regions there is only one weakly acidic deposit, this is increased to three more acidic bands in the proximal regions. These bands can be correlated with materials of different electron density. All five regions have characteristic secretory ultrastructure, with prominent secretory vesicles or granules and microvilli. However, the posterior and middle regions have electron‐translucent vesicles and relatively short microvilli, while the other three regions have electron dense granules and a more complex, microvillate apical surface. This complexity is greatest in the duct which suggests that it may function in water reabsorption.