Fuzzy caterpillar has sting 'like being hit with a baseball bat," and now we know why

Asp caterpillars may look cuddly, but they deliver an excruciating sting that people have described as like being hit by a baseball bat.  (Image credit: Brett Hondow via Shutterstock)

Don't be fooled by the asp caterpillar's innocent look: Its fluffy coat conceals dagger-like spines with a painful venom that hospitalizes dozens of people in the U.S. every year.

Now, scientists have discovered proteins in these caterpillars' venom that may explain how the bristle-covered creatures pack such a punch.