Back in the pre-historic days of early horror movies insects were depicted as huge crawling or flying gargantuan creepy things.  It was as if Hollywood was predicting that a nuclear disaster could in fact result in the human race being eaten by giant insects.  Who can forget the movie “The Fly” which was certain to make even the red-blooded males cringe.

Setting Hollywood aside, let’s look at what conditions are required for humongous insects to exist.  Insects evolved during the Paleozoic period which was somewhere around 500 million years ago and I would imagine the insects (then) were quite large.  How about a dragon fly with a 3 foot wing span on the front of your – oh wait cars were not invented yet.

The reason insects were so big then was due to the concentration of oxygen in the atmosphere.  O2 levels were about 35% then compared to 21% now.  Insects breathing apparatus keeps them from growing any bigger today (thank goodness).

This special breathing apparatus is so amazing – insects have multiple tracheas.  Humans have one.  Try to drown an insect – they can close down certain tracheal areas and still survive on the oxygen in that remains in them.

If an insect were to start to grow, for some strange reason, due to their existing tracheal size being limited, the growth would stop.  Whew – that’s a relief.  Picture your most terrifying bug moment now and picture it with a 3 foot wingspan.

Barring a sudden dramatic rise in O2 levels I think we are safe, thank goodness.