Insect giants escape oxygen-diffusion limits in flight muscles
A cross-species analysis of 44 insect species across 10 orders (plus the 100 g Meganeuropsis permiana) shows the tracheolar space in flight muscles rises only about 1.8-fold over a 10,000‑fold range in body mass and is typically 1% or less. This argues that diffusion of oxygen through the tracheolar–muscle system does not constrain maximum insect size, including gigantism. The study highlights that even a threefold increase in tracheolar space would markedly affect oxygen delivery but have only modest effects on flight, challenging the long-held view that atmospheric oxygen limits insect gigantism and pointing to other factors shaping their evolution.
