More time at the computer led to this conclusion. A beetle can get no bigger than about six inches. And as it turns out, that's about the size of the largest known beetle, the Titanic longhorn beetle, Titanus giganteus, of South America.
If oxygen is the key, does it determine the size of insects over succeeding generations?
To find out, the researchers studied about 10 generations of fruit flies, varying the level of oxygen over multiple generations.
"They get smaller in low oxygen and bigger in high oxygen," adds Harrison, noting that while that may not be a smoking gun, at least it's a "smoking fly."
It's rather unlikely that the oxygen in our air is likely to change dramatically anytime soon, so for now at least we're safe from giant dragonflies that, incidentally, dine on mosquitoes and mate in mid-air.