Are Giant Insects Larger Than Humans Possible?

Science fiction films like 'The Fly' and 'Mothra' will show you giant insects creating havoc and destroying world order with their giantness. But, is that even possible? Science says, not really. When the insect's exoskeleton expands it gets too heavy and it doesn't expand enough for all the muscles of the insect to attach to it. There also isn't enough oxygen for insects to get large; 300 million years ago there was more oxygen and insects were as large as hawks. But, when birds and bats evolved, they began competing with and preying on large insects which led to the small insects we have today.