Gnats or little black bugs in my Flue!!

So I shutdown my furnace yesterday morning. I go to clean it late in the day, unhook the flue pipe that goes to my stainless steel liner, look in the liner and see many dozens of these critters walking around. Can these guys actually come all the way down the chimney like this? Anybody else have a similar situation. They were definitely small black gnats with wings, not termites.

I think that along with the mild winter it's gonna be the spring & summer of the insects. I haven't taken my DV apart yet, can't think of anything that would attract them.

Fire the stove back up.

Fire fixes everything.

They're not Cluster Flies are they?

No, no way cluster flys!