On the fear of insects issue, I once read about a study that was done with monkeys about whether fears were learned or inborn.
As a baseline, they observed that captive-bred monkeys were not afraid of snakes and also not afraid of flowers. So obviously, there’s nothing hard-coded that automatically creates a fear of snakes.
Then they took these monkeys and had them watch some movies. One set of movies showed a monkey in the wild reacting with fear to a snake. Monkeys who saw that movie learned a fear of snakes just by watching. Another set of movies digitally edited the footage so that the wild monkey’s fear reaction was to a flower. These monkeys did NOT learn to be afraid of flowers.
So… while it’s probably not safe to draw any firm conclusions from this, it suggests something in between the nature/nurture dichotomy. While the fear must be learned, it seems that we have a predisposition to learning fear of some things over others.
Decomposing insects smell. They smell bad. You just have to have a lot of them in order to smell it.
Case in point: about twenty years ago, when I was in college, we had a bumper crop of crickets. The little brown-black guys, about two inches long, played violin on their back legs, hopped around a lot. By bumper crop, I mean they were ankle deep on the lawns and most of the sidewalks had a full coating of squashed crickets underfoot. Normally, I’m fine around bugs (except roaches and fleas, because they’re evil), but walking around, having my ankles pelted by suicidal crickets while every step crunched gave me a severe case of the heebie-jeebies. Within a day of this, there was a growing odor from the dead crickets - not the kind of backed-up-sewer smell meaty animals get when they decompose, but a smell that was both dry and slimy, and it stuck to the inside of your head and infiltrated the classrooms.