Conversation with a three year old

Ten minutes after I freaked out about a writhing mass of caterpillars on top of the stroller which was brought to me as I worked at my desk:

William: Mommy, the cadder pillars won't move anymore.
Me: They won't?
William: No. They're dead.
Me: They are?
William: Yea-yuh.
Me: How did that happen?
William: I didn't died them.
Me: You didn't?
William: Nope. I killed them with this boot.