The respiratory currents in the tracheal system of the adult honey-bee

1. The propodeal spiracles of the honey-bee remain closed in normal air but in air plus CO2 they open as the abdomen contracts, and close as the abdomen expands. 2. The first thoracic spiracles remain open in normal air but in air plus CO2 they nearly close as the abdomen contracts, and open as the abdomen expands. 3. When the bee is in normal air there is a strong tidal flow of air in and out of the first thoracic spiracles, but only a weak and variably directed stream of air through the body. 4. It is deduced that when an active bee is producing metabolic CO2, directed streams of air enter the first thoracic spiracles and the abdominal spiracles and leave via the propodeal spiracles.