Dear Tu,

If beetles seem to be everywhere, that’s because they are. Some beetles stand out because they’re colorful. Think about jewel beetles and ladybugs. Others play useful and weird roles in the ecosystem—like the poop-rolling dung beetle. Their ancestors probably even ate dinosaur poop.

Nobody knows exactly how many beetles there are, but scientists have some ideas. I talked about it with my friend Joel Gardner. He’s the collection manager for the insect museum at Washington State University.

When scientists find a new species, they describe what it looks like. They give it a name. They publish that information so other people know about it. That’s called describing a species. Scientists describe new insect species all the time.

Gardner told me scientists have described about 400,000 species of beetles so far. There are many more beetles we don’t know about yet. Altogether, there are probably between 1 million and 2 million beetle species.

Right now, beetles make up 40% of all described insects. They’re 25% of all known life on Earth.

But another group of insects may have more species than beetles—parasitic wasps. These wasps lay eggs in or on other insects. When the eggs hatch, the baby wasps eat the host.

“For every insect there’s probably a wasp that parasitizes it. So, you can imagine there are millions out there,” Gardner said. “Parasitic wasps are generally very small. Different species look almost identical. So, you need to use advanced methods to tell them apart.”

If scientists described all those parasitic wasps, beetles might be closer to 5% of all insects.

Another way to look at your question is how many individual beetles are on Earth right now. Gardner did the math to figure that out.

He told me scientists think there are around 10 quintillion individual insects. That’s 10 followed by 18 zeroes. Like this: 10,000,000,000,000,000,000. If 5% of all those insects are beetles, there are probably around 500 quadrillion individual beetles.

Pretend you’re the beetle boss. You make those 500 quadrillion beetles line up. If they’re all half an inch long—about average size for beetles—that line of beetles would wrap around the Earth more than 150 million times. That’s a lot of beetles.

There are about 500,000 beetles in the collection at WSU. Gardner stores them in 917 wooden drawers. Some were collected by scientists. Others were donated by people who collect insects for fun.

Beetles belong to the order Coleoptera. You can often identify a beetle just by looking at its wings.

Like most insects, adult beetles have four wings. Scientists call their hind wings membranous. That means they’re thin, flexible and transparent. They flap these soft wings to fly. The front wings are hard coverings called elytra. They protect the hind wings. The red-and-black part of a ladybug is its elytra.

The only way to know for sure how many beetles are out there is to find and describe them. One of the best parts of entomology—the study of insects—is that it’s open to everyone. Getting to know the beetles that live near you is a great way to get started. Maybe one day you’ll find a new species of beetle!


Dr. Universe