Fig. 3. CO₂ and O₂ exchange of a Circellium bacchus (mass 8.153 g) from (A) the anterior mesothoracic spiracles, where the majority of exchange occurs, and (B) the posterior metathoracic and abdominal spiracles, which contribute less to respiratory exchange. The readings are from one individual and are matched in time. Negative values of O₂ consumption are due to baseline drift.