Ultrastructure of exocrine prothoracic gland ofDatana ministra (Drury) (Lepidoptera: Notodontidae) and the nature of its secretion.

Datana ministra larvae possess a gland situated in the ventral anterior portion of the prothorax. The gland consists of a single sac and is only charged with secretion in the last instar. Its orifice, a simple slit, opens into a transverse invagination of the integument in the cervical margin of the prosternite. The components of the gland have been identified by GC and GCMS and have been shown to be dodecanol, dodecyl acetate, and dodecyl formate. The morphology of the gland and the chemistry of the secretion are discussed in relation to other notodontid larvae which have been investigated. It is conjectured that the secretion is not defensive in nature but may function as a dispersal pheromone.