oh dear. It's both strange and gross, you've been warned.
Used to live on a farm, it was an old farmhouse and we had both a horse barn and a cornfield less than 50 yards away on either side of us so field mice would get in the house sometimes in winter. One winter we saw signs of mice and I set some traps in the usual places, caught some mice, problem solved. Except there was a smell coming from the living room, couldn't figure out where it originated though. I looked everywhere and eventually the smell dissipated so I forgot about it. One day in the early spring, probably March, we had flies, so many flies! We always had flies getting in the house in warm weather because of how close we were to the barn but this was so much worse than normal, it was gross. Not long after the fly-pocalypse, I started doing some spring cleaning, moving furniture to steam clean the carpets, and there was the partly mummified (but apparently still juicy enough to have hosted maggots to adulthood) corpse of a little field mouse, stuck in a mousetrap behind furniture where I never would have looked for it because for some reason my ex husband decided to set a trap way back out of the way, not in one of the usual spots. A strange, gross, cleaning surprise.