Battling black flies
My rule of thumb is: black flies appear with mother’s day and will disappear with father’s day, which means, they’ll be a nuisance for quite some time.
Not everybody will be attacked by black flies as I am. It depends probably on skin type and blood.
Although black flies belong to the same family as mosquitoes, they breed in streams and other moving water, instead of the stagnant puddles that mosquitoes prefer. While male black flies feed on nectar, the females need blood before laying eggs for a new generation to bother everybody.
Wearing a hat is a good idea and put all the hair under it. They are attracted to hair blowing in the wind. I read about putting sticky tape on your hat to catch them before the act. In Australia they have cords with corks at the end hanging down from the rim of your hat. Those cords move of course when you move, thus chasing the black flies away.
So if you plan a visit to the country between mother’s and father’s day, you should come prepared. May and June in the country are wonderful weatherwise, so a little preparation will help you enjoy when nature awakes with such abundance!