Hi, our horses have colonies of small black eggs in ridges at the base of their necks,
under their stomachs and on the top of their tails.
Sometimes blood drips from them. So far we clean them off and apply fly spray.
I have started using essential oils. This works better than premixed spray.
Only a very temporary fix.
What are they? what can we do?
Your description sounds like trauma caused by Black Flies. What appears to be eggs is likely small droplets of dried blood. Also, the areas that you describe are classic for Black Fly lesions. In my experience, the inside of the ears are often affected, as well, but if the hair is present that helps protect the ears. Unfortunately, I do not have a good fly repellent that I can recommend. Swat seems to be the best or keeping the areas covered with a fly sheet.
Please let me know if you have additional questions or concerns.