Worker bees will eject waste to keep the hive clean. But if the waste is too big to carry out, say a dead mouse, it will instead be mummified.
Beehives have efficient waste disposal systems that would be the envy of most municipalities. Bees carry out anything that could undermine the good health of the hive; there’s even a special class of worker bee that properly disposes of dead bees (the “mortuary bees”).
Unfortunately, sometimes something gets into the hive that’s too big for the bees to carry away. A mouse or a small lizard, for example. Bee mandibles are neither large nor sharp enough to cut up such animals, and a dead and decaying mouse corpse is going to introduce all the joys of putrefaction into the bees’ living / eating / breeding quarters.
So, the bees will encase the corpse in propolis, a kind of bee-produced resin usually used to seal up gaps in the hive. Completely encased in this dark brown goo, the animal body becomes effectively mummified and no longer presents a health hazard to the hive. If you have the stomach for it, you can see a picture of a bee-mummified mouse in the second link below.
I live in Auckland, New Zealand, and am curious about most things.