A new glandular organ in some toxic caterpillars.

The nodes formed by the mid-ventral tracheal anastomoses in abdominal segments 3-6 are modified into conspicuous glandular organs in larvae of certain Lepidoptera. They comprise clusters of extremely large cells penetrated by an extensive lacunar system opening onto the tracheal wall. These cells appear to sequester substances from the haemolymph which may be conjugated with a lipoid synthesized within them and the product excreted into the lacunar system, ultimately passing into the tracheal lumen.