Insects are limited in size because they breathe through their exoskeletons and they can only absorb so much oxygen. About a half billion years ago, the Earth was almost twice as rich in oxygen and there were dragonflies the size of geese, 10 foot long millipedes and cockroaches a foot long weighing in at several pounds. It would take more than a size 11 boot to bring one of them down.
Insects are limited in size because they breathe through their exoskeletons and they can only absorb so much oxygen. About a half billion years ago, the Earth was almost twice as rich in oxygen and there were dragonflies the size of geese, 10 foot long millipedes and cockroaches a foot long weighing in at several pounds. It would take more than a size 11 boot to bring one of them down.