They had certainly caught the eye of a Hummingbird hawk-moth, (Macroglossum stellatarum [1]), which was beating its head against the glass, apparently trying to reach the brightly coloured piles. I imagine they looked like flowers to a creature with compound eyes. We've had hawk-moths in the garden all summer and they are amazingly agile fliers, hovering to poke their long feeding tubes into the kind of flowers which hide their nectar deep inside. There is evidence that they are starting to breed this far north and some to overwinter, but whatever this individual's plans were, they would have to wait until it had a feed, but it didn't look like it was going to find that amid the glass and concrete.
In the time I watched it the moth didn't manage to find the doorway. If it had, it almost certainly wouldn't have been able to find its way out again. Choose your own metaphor for this image, a small moth battering the front of a human construction, because I'm sure there are many you could pick. In any juxtaposition of the natural world and the human, nature usually comes off worse, through no fault of its own. Maybe the moth moved on, maybe it found some real flowers rather than images printed on cardboard. I hope so.
[1] Hummingbird hawk-moth on Wikipedia
Email: kdan01 [at] posteo [dot] net