The present study describes the morphology of the sternum V gland of three caddisfly species, Stenopsyche marmorata Navas, Eubasilissa regina (McLachlan) and Nemotaulius admorsus (McLachlan), each of which belongs to a different family of the order Trichoptera, using light and scanning electron microscopy. In both sexes of these three species, the gland orifices are located on the sides of the sternum V as crescent-shaped slits, and are connected with the glandular tissue via cuticular gland ducts. The shapes of glands differ greatly among species; a slender ampullar form in S. marmorata, a flattened saccular form (horseshoe shape) in E. regina and a kidney shape in N. admorsus. The glands are composed of four essential components: large secretory cells, small reservoir cells, the lining of the reservoir and the gland duct. In S. marmorata and E. regina, additional components, muscle fibers, are present around the small reservoir cells. The secretory cells covering the whole outer surface of the gland are very large, and form many bunches in S. marmorata and E. regina, but do not form them in N. admorsus. The small reservoir cells lie inside the layer of the secretory cells and are tightly connected with the cuticular lining of the reservoir. The linings become thick cuticular ducts near the gland orifices. Histological features suggest that the secretory cells of the sternum V gland of Trichoptera belong to the type of class 3 cells in insect epidermal glands.