I came across this book after taking Nathanael to see the butterfly exhibit at the Academy of Natural Sciences of Drexel University in Philadelphia. What a fun experience for toddlers. I'd highly recommend it.
In any case, I came across the book in the gift shop and while it's simply a color/counting book, the illustrations by Shennen Bersani are really lovely. Nathanael particularly likes it when I open and close the book (ever so slightly) to make it look as though the butterflies are actually flapping their wings. A fun book all around!
The book also provides the names of the different types of butterflies on the back cover, which is very useful (especially for someone like me who isn't up on my butterfly species!).