In an effort to understand the makeup of Earth's prehistoric atmosphere, a group of researchers has been trying to grow insects as large as their giant ancestors. It's all fun and games until they start overrunning the countryside.

Ancient Earth saw dragonflies with wingspans up to 28 inches, and their size is thought to be linked to higher levels of oxygen in the prehistoric atmosphere. Now John VandenBrooks of Arizona State University has tested that hypothesis by growing himself some big bugs.

VanderBrooks raised groups of dragonflies, cockroaches, grasshoppers, meal worms, beetles, and other insects in atmospheres with different levels of oxygen. As predicted, the dragonflies and many of the other insects raised in higher oxygen matured more quickly and became larger adults; when these same species of insects were raised in atmospheres with oxygen levels lower than modern Earth's they grew to be smaller than those reared in modern atmosphere.

There was, however, a significant exception. Ancient cockroaches were no larger than modern ones, and in VanderBrooks' experiment, the cockroaches grew no larger in higher levels of oxygen. In fact, the cockroaches raised in hyperoxia stayed in their larval stage longer, as if waiting for less oppressive levels of oxygen. So at least this particular bout of mad science won't end with giant roaches raiding your pantry.

Raising giant insects to unravel ancient oxygen [PhysOrg via DVICE]