We have a major fly problem every summer, with of all things, Cornish Tin Mine flies (In Essex lol) These horrible little **** bite the dogs noses and ears until they actually run with blood. The vet and I have tried just about everything possible, with no success. A friend who lives in Devon, suggested Lavender oil, not diluted, dabbed on ears and noses twice a day. This didnt cure the problem totally, but helped an awful lot. It dosnt help much keeping the dogs indoors either, as the flies come in and bite us too! Really wish I could find a total cure, but I dont feel I ever will, so each July is a pain in the ***

Maybe trying the lavender oil on your animals may help a bit too.