Fig. 2. Temporal occurrence and frequency of cyclic gas exchange patterns in flying Drosophila. (A) Cyclic gas release often consists of multiple consecutive CO₂ release cycles in a burst (gray). (B) Frequency of occurrence of cyclic bursts containing different numbers of cyclic CO₂ `waves'. N=12 flight sequences, as shown in Fig. 1C (12 flies). (C) Frequency of consecutive CO₂ cycles in a single fly. (D) Mean frequency of CO₂ oscillations measured in 12 flies. Red dotted line, mean value derived from all 12 flies. Values are means ± S.D.