I do a four-day trip with boys the first weekend of May every year and have done since 2005 in French River PP. On a couple of occasions the trip was in the second weekend of May. On one those two occasions there was slight evidence of the black fly hatch. But they were few and not biting. The usual spring barrage generally commences in this are around mid-May.

NEVER on the first weekend of our May trips have we seen any BF action until this past weekend. They were out and bothersome on May 2 and swarming and biting by May 4. Not in full force, but it wasn't pleasant.

It has been very wet in this location and it sounds like similar wet weather was experienced near Quetico/BW. I'm not sure if the very early hatch will translate to that area but at least you can say you haven't been warned. Watch the bug reports and be prepared if you plan your early trips to avoid these vermin. You may not be early enough. Pack your bug shelter.