Here's a question for you:
Why do cockroaches always seem to die on their backs? ...Oh, don't make that face. If you live in Houston, you've found a dead cockroach in your house at some point in your life. And when you've found that poor dead critter, I bet it was on its back.
So, in my somewhat morbid curiousity, I looked it up.
Here is the boring answer that makes me feel slightly guilty for my slick, polished floor and the insecticide the twitch inducing insecticide. Here is a more humorous and slightly less guilt-inducing answer.