Parah 9:2-3

Parah 9:2

If insects or vermin fell into the flask of sanctified water and they broke apart or the color of the water changed, the water is invalid. If it’s a beetle, it invalidates the water in any event because it’s like a tube (i.e., the water passes through it). Rabbi Shimon and Rabbi Eliezer ben Yaakov say that certain grain insects do not invalidate the water because they contain no moisture.

Parah 9:3

If a domesticated or wild animal drank from sanctified water, it is invalid. All birds invalidate the water (by drinking from it) except the dove since it sucks up water (without salivating into it). No vermin except the weasel invalidate the water (by drinking from it) except the weasel since it laps up water (which causes it to salivate into it). Rabban Gamliel also added the snake because it regurgitates; Rabbi Eliezer also included the mouse.