I am trying to plan my vacation for next year and wanted to know when is black fly season over in the White Mountains.
No one is jumping in here so I'll give some input (FWIW). On July 22nd 2010 I was at Duck Pond (~3000 ft) in the evening and the black flies were trying to carry me away like the flying monkeys in the Wizard of Oz. I don't normally care about flies and "squitos" cause their bites don't bother me, but I still have to inhale once in a while. I used my head net for the first time ever.
The 10mph wind across the pond did little to deter the buggers....any letup and the cloud returned. I felt a little like Pigpen.
That was the first and last time I really noticed black flies this year, but it was pretty late in the season.
I agree, they were pretty heavy at that time as well, and I was in the North Country on Cabot and Waumbek. I find that a good healthy dose of super potent bug dope helps, however a headband might be in order, cause if you get caught in a thunderstorm as we did (which took away the bugs) it will run down your face and make it difficult to run back to the car when you're eyes are burning and you can't see where you're going : ) It all depends on the territory of course too. Wherever you are, even armed with bug spray, the swarming alone can drive a person nuts. I actually found, as strange as it was, that if I stopped for a minute, they would leave me alone. Once I started moving, they swarmed. I don't understand it. This was not the case on Moriah though, where you couldn't stop for 2 seconds without wanting to cry. And I had to stop constantly to wait for the 'slower' hiking partner to catch up. Made me want to carry her! I find that this site: http://www.newenglandtrailconditions.com/ is great for getting up to date trail conditions, including bug count.