Your post made me think about something I saw the other day on Facebook.
This is from some animal clinic:
flybites.jpg We are having lots of calls and visits for these red spots on dogs. These are black fly bites and will fade and go away in 3-5 days. They look bad but do not require treatment. They are not painful and do not itch. They most commonly occur on the belly but can show anywhere a fly may bite.