The 5 Most Horrifying Bugs in the World | Cracked.com
Nick Griffen stashed this in Fear
KILL IT WITH FIRE!
Those bugs are pretty badass, but 300 million years ago (during the Carboniferous Period when the concentration of oxygen in Earth's atmosphere was higher) there lived the greatest insect the world has ever known:
It had a wingspan of 2 feet and was an apex predator.
Model of meganeura, from Wikipedia.
I believe that the heaviest insect alive today (though they are harmless), is the Giant Weta.
It can have a mass of up to 70g.
Wetas are pretty awesome. They just don't seem as sinister as spiders though. Which is terrible because spiders perform such a useful function in the world. Life is confusing.