Very cultural - plenty of cultures roast and eat certain insects, and Western culture's prized crustaceans (shrimp, crab, and lobster) make me ill pretty quickly after eating them - and many of them look like big insects. I was unpleasantly surprised to learn that Malaysian Muslims have no aversion to shrimp and happily include them in sauces; I'd always figured that halal food was pretty close to kosher, and there was at least one category of restaurant in Singapore I could let my guard down at.

There are two kinds of animal food aversions: disgust because the creature itself is considered disgusting, and horror because the creature is more often considered a companion animal or otherwise special. Anglo-Americans generally have a strong aversion to eating both mice and guinea pigs (horses, dogs), but for those very different reasons.

There were several cheese types in Britain that were traditionally full of maggots, and eaten that way. Modern food production techniques and refrigeration has allowed us the luxury of strong insect aversions.

In parts of Colonial America, prisoners and slaves were fed lobster, and free servants' contracts often stipulated that they wouldn't be fed it more than a certain number of times per week, because people with a choice didn't want to eat them. Cultures change! Now lobster is a luxury food everywhere in the US other than the areas they're caught in, where it's a cultural pride food.