none A simple model demonstrates for the first time how quickly flowing water aids in catching air bubbles at pressures below atmospheric pressure, according to Bernoulli's equation. Respiration; Behaviour; Ecology; Animal constructions; Abiotic factors; Chemical factors; Physical factors Agriotypus armatus (Ichneumonidae); Accessory respiration; Respiratory function; Larval cocoon air space; Air filling effects, influence of flowing water, model; Orientation; Cocoons; Larval cocoon; Gases; Air; Water movements; Flowing water