1. The diuresis of freshly fed larvae of Rhodnius is controlled by afferent nervous information from the abdomen.
2. This information is supplied by abdominal stretch receptors sensitive to vertical distension of the abdomen. It is most probable that the receptors are in the vertical tergosternal muscles, a trio of which occurs towards each lateral edge in abdominal segments 2-7 inclusive.
3. It is suggested that diuresis in Rhodnius is a reflex response to the distension of the abdomen brought about by the swelling of the anterior part of the mid-gut during feeding.