Black Flies lyrics

This song is about an old love of the singers.
"black flies on the windowsill" refers to flies that have tried and tried to get somewhere but have failed because there has always been something in the way (the glass). This is a metaphor for the relationship with the woman that this song is about. These two people have tried again and again and again to make things work yet there was always something in the way to stop them and eventually after giving it everything they have they are left motionless - emotionally dead.
"winter stole summers thrill" refers to how their relationship once was and where its ended up. What was once a radiant happy summer was overthrown by the negativity of the winter - the good times where overlooked because of the bad things happening around them.
"see the sky is no man's land, a darkened plume to stay, hope here needs a humble hand, not a fox found in your place" shows how although the singer has moved on, no one can fill the void left by his previous love. Another woman is but a fox by comparison.
The song continues along these lines throughout the rest of its entirety. He shows again how much he feels for this girl and how he'll never be the same without her. He'll forever be a black fly on the window sill because he's given all that he has to try and be with her.

Pure love. Seriously. It's amazing!!! Ben howard is amazing. Amazing amazing amazing.

I do not have a clue at all. Someone please tell me?! ):