I would love to see a graph like that!  The only thing I can tell you is that in August – if its been dry – there are generally many fewer bugs.  I have been to the Allagash in September when it was wet and the bugs were back.  Its been fairly dry, so bugs shouldn’t be too bad right now.  Someone who has been there recently may have better first-hand information.

[Update:  8/17/26 — Alyson and I just got back from 3 days on the water.  Nary a bug in site!  It was wonderful]