Godzilla arrives for a ceremony to receive his star on the Hollywood Walk of Fame Reuters

Egad!, someone get us a giant fly swatter. According to a post at Wired, biologists have grown super-size dragon flies that are 15% larger than normal by raising the insects in high-oxygen conditions that mimicked the Earth’s conditions 300 million years ago.

Back then, apparently, in what is called the Paleozoic era, dragonflies had wingspans stretching more than two and a half feet—more like a dragon than a fly. Scientists have long speculated that the reason for the era’s mega-insects was that the planet’s atmosphere had roughly 50 percent more oxygen than today. So in order to test this theory, paleobiologist John VandenBrooks of Arizona State University raised 11 so-called “living fossils”–species that lived through the great extinction events to make it through to present day—in different oxygen environments.

He found that dragonflies grew faster–as well as bigger–when they hatch and grow in oxygen-rich tanks. Ditto beetles. Cockroaches— reliable little buggers that they are— grew to essentially the same size no matter the oxygen content, although the pace of their growth changed.

Although VandenBrooks’ dragonflies did not make it to disaster movie proportions–I still favor Tokyo’s police department’s chances against even a 15% bulkier dragonfly—VandenBrooks says he next wants to test the effect oxygen has on the creatures’ behavior—specifically their “speed and efficiency.” So next up: Giant, super-fast bugs. DEET shower anyone?

(See TIME’s story on how Super-Crocodiles dined on Dinsoaurs)

(Read: Maybe an Asteroid Didn’t Kill the Dinosaurs)