We went Labor Day week and went out on the beach around 9:00 a.m. and couldn't sit there 15 minutes. They say those flies come in when the winds are out of the north. They are what they call dog flies. Look just like the black flies here. But these don't bite. Couldn't even walk the beach in the evening before dark without having to slap at them on my legs. And no repellant works agains them either, not even Deet.