Fig. 8. Flight force development and CO₂ release dynamics during flight initiation in three different respiratory conditions. (A,B) Flight force development (A) and respiratory gas release (B) in three single fruit flies starting flight from rest. Black trace, unmanipulated flying animal; red trace, metathoracic spiracles sealed on both body sides; blue trace, all thoracic spiracles sealed. *Resting periods of Drosophila, in which gas exchange was restricted to abdominal breathing (blue). CO₂ release rate is given in parts per million (p.p.m.) analysed air. Arrow indicates stimulus artefact (under pressure peak) resulting from the experimental procedure we used to elicit flight. Vertical grey area indicates the time in which the unmanipulated fly transiently produced forces in excess of hovering force.