I'm looking for a Golden Book
that had a picture of
a little boy looking at a caterpillar
on the cover.

Thanks!

Actually, that's a little girl on the cover of Wonders of Nature. There's another Little Golden Book, also illustrated by Eloise Wilkin, titled Jamie Looks, #522, c. 1963; the cover shows the little boy, Jamie, looking at a small creature in his hand. The picture in Santi's reference book "Collecting Little Golden Books", is too small for me to tell exactly what he's looking at in his hand. I've got the book but haven't taken the time to check through all my LGB's to find it. But probably the book you're wanting is one of these two.