What can I do to stop flies from biting my dogs?

Cindy! I have 5 g/s dogs and every year in the summer the flys attack these dogs' ears. I also see an increase in bees. We tried the fly off paste and spray, It works for about 5 mins and also the other dogs like to lick it off each others ears. My one female that's about 14 years old is missing the tops of her ears from all the years that this is happening. I also have a long hair male pup that is getting his nose attacked. His hair is to long for them to get to his skin. The pen that they are in is 30' by 40' all blacktop. I keep it very clean and put the chemical down called trail every other day for the smell, but the cost is pricey. I had gone on a website about the history about flys, it was quite interesting! The one thing that they said is that they are attracked to the color white. Well, my building is white. I also notice that the cars that around me have flys on them and they leave little dots like droppings. If you wet them it's blood. The cars that aren't white also have the same but not as noticeable. The flys also follow the dogs to a different environtments (my home).

In closing, I just want to let you know even though my dogs are outside I keep them very clean, give them bathes and they have a good diet. I have heard several ideas for this problem, but noting to date has worked. Please can you give me an answer as to why this is happening, what to do to relieve the suffering fot these dogs. Thank you in advance
for advice you can give me.

Ed