I suppose what swings it against the poor old maggot is that it prefers to dine on rotting flesh, whereas the cute little caterpillar eats shoots and leaves (as opposed to eats, shoots and leaves, or eats, shoots, and leaves if you happen to be American. Have we all read the book? I haven’t.) Anyway, I assume that its preference for a scavenged carnivorous diet endows it with an association with death and smelly things, so that’s why we turn our noses up when we see one. (Bit like meeting a corporate executive, really.) And when we see lots of them we screw our whole faces into ugly shapes because we have a genetic memory of maggots en masse being associated with battlefields and charnel houses. Or so I suppose.
I don’t generally mind maggots. If I had a festering wound and a doctor said that maggots would be the best cure (as they often are, I believe) I’d be quite happy to accede to the suggestion. I grew up with them, you see. My favourite occupation as a boy was fishing, and I found that maggots made the best bait. Sometimes, when the fish weren’t biting and I was bored, I’d place a few maggots in my hand and watch them crawl between the gaps at the base of my fingers. It seemed a matter of some as-yet-unknown significance to me that a maggot would crawl through a hole, disappear, and then reappear underneath. I was bit unusual like that.
In fact, I grew so fond of them that I eventually had an ethical crisis at around age 25. I decided that sticking hooks into the poor things and dangling them in the water to either drown or be eaten was unacceptable. It was one of the main reasons why I gave up fishing. I'm still a bit unusual like that.