Yes, I'm like two or three years late. Leave me alone. The concept for my AU was basically a body takeover. The larvae would be transferred through a bite. So it's not the bite that causes "infection"; it's the larvae. It goes to the host's brain and basically "bonds" to it. Stage 4, as depicted above, is what a full bonding looks like. The larvae and the host are completely one. The "bugs" reproduce asexually through parthenogenesis within the host.
Some other notes, if you can't read my handwriting, are that the host is deaf and blind at stage 4, so the antennae and little "hairs" help it sense things. At stage 4, their lifespan is shortened. I haven't really decided how long, though. If the pony happens to have wings or a horn, they will not work. Completely useless, so no worries about an infected casting magic. They possess bile sacs that they can expel on a target. It essentially marks the victim and also makes them vulnerable because of its potency. That's all I can remember off the top of my head.
