I've eaten a variety of invertebrates raw, including slugs, earthworms, maggots, ants, mayflies, and beetle larvae.
Slugs are very spicy (at least the ones I've eaten), maggots are subtly sweet and take the taste of what they're eating (I've picked them off deer carcasses, and have 'raised' them on fish that have been filleted in summer), ants taste like lemon candy because of the formic acid in their stingers, mayflies remind me of spinach, and beetle larvae have a variety of tastes and textures depending on the species and where it's been living. Earthworms don't have much of a taste, as I generally don't chew them, just swallow, so I don't have to bother clearing their guts of grit.
I suspect that prior to inventing projectile weapons, invertebrates--including insects--made up the majority of the animal protein that our species consumed. Think about it, we can't run particularly fast, don't have fierce teeth or claws, so in the absence of spears or bows & arrows how would we have gotten meat? Answer: we wouldn't, except for the rare instances when we found a dead animal another species had killed and we manage to chase it off. Prior to developing projectile weapons, we were probably more often the prey than the predator, except as regards invertebrates and perhaps fish.
I think our aversion to them is largely cultural. We've spent too long as Homo domesticus, and have been socialized to ignore an enormous and free source of high quality fat and protein in favor of ruminant meats that we have to pay for (and thus participate in wage slavery to earn). Accepting invertebrates as part of our diets is a step towards dietary freedom, in my opinion.
Suggestions on acclimating: start by eating a live ant, perhaps a carpenter ant. Don't try a fire ant, or an army ant, or a bullet ant if you live in tropical areas, or a velvet ant if you live in temperate regions. Find a field guide that covers your region to learn at least the groups of ant species, and avoid the ones that give nasty stings.
Next step might be to set aside the beetle larvae you find when gardening, or to turn over logs in the forest and pick a few from the dead wood (you'll most likely find lots). Beetle larvae come in all shapes and sizes, and most look vaguely like caterpillars. Crush their heads before you put them into your mouth, otherwise you risk being bitten, which doesn't hurt particularly but most people aren't used to getting bitten by food so it could put you off. The huge grubs that African natives relish are beetle larvae. On that note, some caterpillars are edible, but not all, and some will give you a hellish sting or are quite toxic, so be careful. I personally have never eaten a caterpillar and don't know their taxonomy well enough to try one.
Spring, summer and fall is the time for mayflies, so if you live in temperate regions with decent water quality, this is the time to feast. I've read that indigenous tribes in North America would go to war over mayfly harvests. Given their seasonal abundance and pleasant taste, I see why.
Most of the invertebrates I mentioned above are largely parasite free, at least in terms of parasites that can potentially become pathogenic in people. Learn about invertebrates first, and try ones you can find at least a few sources that claim them to be edible (besides me).
Happy trails!
