The Biggest Insect Ever Existed Was A Giant 'Dragonfly'

Atmospheric Density And Oxygen Levels The way in which oxygen is diffused through the body of the insect through its tracheal respiration system puts an upper limit on body size, which ancient insects seem to have far surpassed. Harlé (1911) originally suggested that Meganeura could only fly because at that time the atmosphere provided more oxygen than the present 20 per cent. This theory was initially rejected by fellow scientists, but was more recently approved through further analysis of the relationship between the availability of gigantism and oxygen.