"You wouldn't like me when I'm angry..." OR "Dr. Jekyll and Jiminy Cricket"
I'm a collector of odd facts. I remember hearing this one some time ago, about how grasshoppers morph into brutal locusts under certain conditions but I find that often the "facts" you hear word of mouth aren't always factual. (Unfortunately, a lot of facts in those 1001 Fascinating Fact books are often wrong too... I've thought of writing a 1001 Fascinating Falsehoods [you thought were facts!], but I'll just have to add that to my to do list.)