The Biggest Insect Ever Existed Was A Giant 'Dragonfly'

If this hypothesis is correct, these insects would have been vulnerable to declining oxygen levels and in our current atmosphere could probably not survive. Some research suggests that insects breathe with rapid cycles of compression and expansion of trachea. Recent analysis of modern insects and birds ' flight energetics suggests that both the oxygen levels and air density provide an upper bound on size. There was some controversy over how Carboniferous Period insects were able to grow so large.