I found a couple of these large caterpillars very near to each other. First the one above and then the one below. I believe they are a species of Automeris.
With those spines and colors, it’s pretty obvious they are to be avoided. Each one of those spines is like a little hypodermic needle bearing venom.
Here are some closeups.
And here’s a particularly intimidating display.
So what would mess with this spiny critter? I discovered while reviewing photos of the latter caterpillar that there was a small fly up to no good. Sorry for the photo quality. These are extreme crops.
I’m pretty sure that’s a biting midge in the family Ceratopogonidae. Some, like this one, will feed on the blood of other insects. I actually found a reference and image of one feeding on a related caterpillar.
Subjects: Biting Midges, Butterflies and Moths, Caterpillars, Flies, and Insects.
Places: Brazil, Caraça Natural Park, Minas Gerais, and South America.
Behaviors: Feeding and Parasitism.
Life Stages: Adult and Immature.
Taxa: Class Insecta, Family Ceratopogonidae, Family Saturniidae, Genus Automeris, Order Diptera, and Order Lepidoptera.
Colors: Green, Purple, and Red.