Horse Botflies

Bot Fly: Definition
Bot fly (family Oestridae), often spelled botfly, is any member of the Diptera order whose adults have a beelike look and are hairy but lack bristles.
Botflies are huge, hairy insects with thick bodies that resemble bumblebees. A mosquito, or occasionally another bug, lays the botfly egg. The larva grows until it is rather enormous inside the host’s body. Adult botflies do not feed since their mouthparts are nonfunctional. In most cases, the parasite does not cause significant harm to the host. When the larvae depart the host through the warble, the majority of the damage occurs. The botfly’s parasitism has little effect on the rabbit’s edibility (if you eat rabbit), and the area adjacent to the warble is usually clipped away, leaving the rest of the rabbit edible.