small flies hatching in late summer?

[kauriel]

The past week or so I've had tons of little fly-like creatures dead in my pool with some larger ones as well (I'm guessing they might be the parents). Any idea what might be hatching this time of year? The bigger ones look like they have some brown on them but the little ones just look like little black flies to me/specks on the pool skimmer.

Part of the reason why I am so curious is because our cedar tree nearby is losing it's needles and also has twigs coming off with white growths - like it has berries or sacs of some sort. Attached is a picture of the twigs that have been dropping (don't mind the green turf in background). No idea if these are related to the little bugs or not.