I would vote for #2. The image of the beetle, combined with the cover text, gives you an idea of something sinister and creepy going on within the book, and uses imagery I don't already associate with something else. #1 is the nicest looking image, but I feel like if I were to look through my bookshelf right now I'd find a handful of books with nearly identical covers. #2 is the most distinctive image.
I would vote for #2. The image of the beetle, combined with the cover text, gives you an idea of something sinister and creepy going on within the book, and uses imagery I don't already associate with something else. #1 is the nicest looking image, but I feel like if I were to look through my bookshelf right now I'd find a handful of books with nearly identical covers. #2 is the most distinctive image.