Thank you for the picture of Chipper's lesion. It appears to be a black fly bite. These lesions from the bite look bad, but typically they do not bother the pet. You don't need to do anything to treat it, these usually go away on their own over time. That being said, if this doesn't improve over the next week, it looks worse, or he's constantly itching it, then he will need to see a vet. I hope this helps!