a. Put on some shoes/protective gear, go back downstairs, hunt it down, and throw something at it
b. Stay up here, in hopes that my cat eats it by tomorrow (and that I don't get hungry between now and then)?
Other suggestions also welcome.
ETA: I just looked downstairs, and my cat is sitting placidly. DID SHE ALREADY EAT IT??? OR IS IT LURKING UNDER THE COUCH?!
Never mind. I just saw my cat eating it, hooray! This is why I like having pets.