That is not a bot (a fly larva) if thats what you were thinking. That looks like a possibility of 4 things.. 1- Cat fight Wound, 2-Fence wound (fell onto a fence post or something), 3- Possible Bullet hole, or 4- Absess. The main thing is the cat will probably need to have the wound shaved, will need to have it cleaned out with some chlorihexidine and will need to possibly have a drain placed. They will also put the kitty on some antibitoic (probably clavamox).