ANSWER: The pear turns into stinky soup in the bottom of said backpack, and you have yourself a nice colony of fruit flies in your house.
We've been finding fruit flies in the house for a few weeks, and it's been such a mystery where they came from. I just assumed they came in from outside. WRONG! On our way home from Disney World the first week of MAY, I had tucked a pear in my backpack to eat on the plane. Fast forward five weeks, & I was cleaning things up in the laundry room, & I moved my backpack and WOAH! A swarm of fruit flies came out. I knew instantly that I had forgotten that darn pear in the bag. Ugh. So, I've been spending lots of time the past two days catching the fruit flies mid-air with some glue traps I have. Works pretty well, but there's just SO many of them.
It reminds me of my Sophmore year in high school, in AP Biology, and we did a gene project with fruit flies...mating particular characteristics (red eyes, white eyes) to see what would happen after multiple generations. It was actually lots of fun, and all the fruit flies in our lovely colony here have red eyes :) Gross. Check out the fruit fly stuck on my glue trap paper: