The Bees,to Watership Down is an almost irresistible temptation, and probably made a pretty good elevator pitch for the book, but to do so, to simply say "bees instead of rabbits" is to sell both novels short. Yes, they're both magnificent novels that are much, much more than human stories acted out by animals, but that's pretty much where the similarities end.
The Bees concerns the life-span of one individual worker bee, Flora-717 (Flora is her "kin"; there are hundreds of Floras and she is but one. But...) within the larger life of a domesticated hive kept by a human beekeeper to pollinate his orchard (his sole "Visitation" to collect some honey is a terrifying scene I'd pit right up against the harrowing extermination scene from the animated film version of Watership Down, but it's somehow more horrifying because the reader knows the beekeeper believes he's a kindly husband to his hive, its benevolent father-god just collecting his tithe).
From her emergence from the cell in which she metamorphosed from a larva to an adult worker bee forward, Flora-717 (or just Flora; other members of her kin group are referred to as floras with a lower case "f" for clarity) is marked out as different. A member of the lowly sanitation caste, she is already considered ugly and brutish, but she's also huge for a worker bee, so huge that the "fertility police" almost kill her as deformed. Only the experimental kindness of a high-caste "Sage" (of royal kin) saves her, and sets her on her unique path.
Flora gets to be a nurse in the royal nurseries for a while, then goes back to janitoring, then gets the opportunity to join the elite corps of "foragers" -- the bees who fly out in search of new sources of nectar and pollen and come back to the hive to dance out not only directions but also detailed stories about how they found the food and what terrors they encountered -- crows, wasps, spiders, cell phone towers* -- on the way there.
All of this is presented with great attention to our current actual scientific understanding of bees and beehives, which lends a lot of plausibility (and earns a lot of willing suspension of disbelief) to Flora's story. At times, though, Paulli can't help herself. These bees "talk" in perfect English sentences and, furthermore, have a powerful form of telepathy that is kind of top-down in that higher caste bees seem to have greater ability than lower but also allows our heroine to download a whole load of knowledge from a dying forager bee at one point. One may snort at this, but let it go.
The prose is lovely, and so is the emotional journey of our Flora as she experiences both a sexless and sexual life of a kind, motherhood of a kind (only the Queen is supposed to breed, but as we've established, Flora is special -- and her origins, if not how she learns of them, plausibly explain her specialness) and life as a tiny part of a greater whole. I'm not at this stage 100% sure that I'm going to read this one over and over again as I have the rabbit book, but since I do happen to love insects rather a lot more than I do rabbits, well...
Anyway, as the best entomological fiction to hit the book world since Clark Thomas Carlton's Prophets of the Ghost Ants, this one is not to be missed!
*A whole thread that entertains all of the suggested and accepted factors that contributed to colony collapse disorder is present here. Paulli wisely favors none of the theories specifically, nor does she get didactic about it all; it's merely texture, background detail on what the life of bees must actually be like. Well, what it would actually be like if they "spoke" and all.