The smell of dead grasshoppers and crickets is distinctive. We had a couple of really bad years in Central Texas back in the early 1980s and the municipality would spray at night. You'd go to a store and walk past piles of dead bugs.

We almost had a dead squirrel yesterday. The girls are beginning to coordinate their routine and they were within a whisker of catching one reckless squirrel that didn't decide it would be smartest to stay up the tree. Dead squirrels stink also, though when I find those things I toss them into the creek for the turtles and fish or bury them in the compost pile.