The fine structure of sternal pheromone glands in the two caddisfly species from the Rhyacophilidae and Limnephilidae families (Insecta: Trichoptera)
To study the ultrastructure of cells forming sternite pheromone glands of the 5<sup>th</sup> abdominal segment of caddisflies <i>Rhyacophila obliterata</i> (Rhyacophilidae) and <i>Chaetopteryx villosa</i> (Limnephilidae) transmission electron microscopy was used. The glands have been shown to be formed by cells of three types: secretory, canal and hypodermal cells. A combination of secretory and canal cells form a unit where secretory cells produce their secret, canal cells form receiving and conducting cuticular canals which take part in releasing the secret into a cavity of the gland cuticular reservoir.