I like this little book that is at the 2nd Grade reading level. The pictures are bright and interesting and it's actually covers quite a bit of material.
Each page features a picture and one or two sentences in fairly large print. Here is some sample text from one page:
Spring is the time to begin laying eggs.
Female monarchs lay their eggs under leaves of milkweed plants.
This book discusses the life cycle and migration of Monarchs. It has a map of where they live and a diagram of the parts of a butterfly.