Water balance across the cuticle of a soil insect

The water regime in soil commonly approaches equilibrium of water potential with the insects living there. 2. Even under these conditions, non-equilibrium processes have a significant effect on water movement through the cuticle of soil insects. 3. Measurements of water potential on either side of the cuticle of Costelytra zealandica larvae showed that equilibrium is not reached while the insect is alive. There is an active outward flow of water by thermoosmosis associated with the flow of heat from the insect.