On Sunday, my wife Susan and I were riding our bikes on Beach Drive in Rock Creek Park when we noticed a group of people kneeling next to something on the road, talking excitedly.

As we got closer we could see the object of their fascination.

Crawling slowly was an exotic aqua green caterpillar that was at least five inches long and half an inch wide. The caterpillar had orange and black “horns” and “eyes” that made it look as if it were wearing sunglasses.

This was no ordinary caterpillar.

Some quick research on the internet revealed that the creature was a “Hickory Horned Devil,” which is the largest caterpillar in Maryland, according to the “Bug of the Week” website, which is produced by Michael J. Raupp, a professor of entomology at the University of Maryland. (Yes, there really is such a website and it’s fascinating.)

In September 2009, Raupp named the Hickory Horned Devil the “Bug of the Week.”

According to Raupp, the caterpillar is fierce looking, but harmless, and exists all along the Eastern Seaboard. When we saw the caterpillar cross Beach Drive, it was probably in search of ground to burrow in. (The bikers who found the caterpillar, moved it to the ground on the side of the road—out of harm’s way.)

Once it’s in the ground, the caterpillar will construct a cell and wait out the winter as a pupa, Raupp says. In the spring, it will emerge as a giant moth, that goes by the names Regal moth and Royal Walnut moth. The moth, which is grey with orange stripes and off-white splotches, can grow up to six inches long and is the largest in North America.

Over the last 20 years, I’ve biked or run in Rock Creek Park hundreds of times. I see deer virtually every time I run on the trails in the park, and an occasionally a black snake or fox. But I’ve never seen anything as exotic (or interesting) as the Hickory Horned Devil.

What’s the most exotic creature you’ve seen in Montgomery County or nearby?