This poor kitten had it in the belly. There are 30+ species of botfly in North America including the house Botfly, the caribou botfly, the mouse botfly, (there’s even a human version in Central America!) The flies lay eggs along branches where animals are likely to run past and pick up the eggs in their fur. The larva then enter through any bodily orifice and establish a warble (hole under the skin) where they grow over the course of the next four months.
They don’t eat or hurt the animal. In fact they want their host to live because they can’t survive in a dead host. So while warbles may be unsightly to us and supremely uncomfortable or itchy to the animal hosts they’re a natural part of our local biology.