Amazon.com has many catagories of best including Best-Sellers-Books-Childrens-Bug-Spider. The top seller is The Very Hungry Caterpillar by Eric Carle. Amazon.com lists books, not stories and the “board book” version is #1, different hardcover versions are #11 & #12 and the Spanish Language version, La oruga muy hambrienta is # 13. Two other books by Carle appear on the Top 20 list, The Grouchy Ladybug and The Very Busy Spider giving Carle books 6 of the top 20 spots. No other author appears more than once except The Snail and the Whale by Julia Donaldson at #3 and #15. At Amazon.com snails are classified as bugs.
The National Geographic name is on 2 books, National Geographic Little Kids First Big Book of Bugs (#9) and Ants (#16). These books showcase insect photography with explanatory text.
Longer fiction classics: Charlotte’s Web #2, The Cricket in Times Square #5 and James and the Giant Peach #6 have been popular for many years. Fiction often uses characters who have the outside appearance of insects but their behavior is part human or presented in human terms. These books make insects more presentable and more compelling to readers who are not generally fans of insects.
Best Seller Lists are useful guides to what other readers find compelling and are a shortcut to find the book you might like the most. The Best Sellers lists tend to be self-reinforcing. Books on the list are more likely to be purchased than books not on the list and some very good less well known books have a hard time breaking through.