‘Caterpillars Killed Dinosaurs’ Theory Is Interesting, Probably Incorrect

There’s a theory floating around that caterpillars killed dinosaurs, and, while the theory is interesting, it is also probably incorrect.

The caterpillar theory is explored in Brian Switek’s new book My Beloved Brontosaurus. In the publication Switek explores a “slew of weird ideas” that were suggested 50 or 60 years ago. The theories in the book were proposed before the current favorite “asteroid extinction” theory was accepted by many scientists.

The caterpillars killed dinosaurs theory was developed by entomologist Stanley Flanders. The “bug guy” wrote a 1962 paper called Did the Caterpillar Exterminate the Giant Reptile? In his paper Dr. Flanders proposed that dinosaurs and their huge hunger for plants couldn’t compete with a giant influx of butterflies and moths.

According to Flanders “the inherent weakness of the reptile was an extraordinary need for an abundance of plant material.”

Flanders argues that caterpillars appeared as a new type of insect and ate large amounts of leafy materials. While butterflies and moths today have had their populations reduced by enemies and parasites Dr. Flanders contends that because they were a new species they did not have natural enemies to slow their population growth.

Dr. Flanders points to a new type of caterpillar that was introduced to Australia in 1925. That Argentina-based caterpillar destroyed 50 million acres of the prickly pear in just six years. The Argentina-based caterpillar had no Australian enemies when it was first imported.

Because the dino-aged caterpillars had no natural enemies when first introduced, Dr. Flanders suggested:

“The giant reptiles which had survived during eons characterized by great changes in climate, continental uplifts, and different diets, may have been exterminated by the lowly caterpillar.”

While the theory of butterflies and moths taking over like a swarm of locust seems like a cool idea, scientists note that no fossilized evidence has been discovered to suggest that such a large population of the insects existed.

It would be interesting to see what Dr. Flanders would think about his theory today, after all the asteroid suggestion was not discovered until years later.

Do you think caterpillars killed dinosaurs? Yeah, us either.