Interesting little game! I would give the webs some sort of visual clue when they are about to expire though, as they kind of disappear out of nowhere at the moment. Another aesthetic choice I would suggest for polish would be to rotate the spider according to the surface it's clinging to, but that's really just a nitpick. The one gameplay complaint I have is it's kind of hard to intuitively tell where to put a web in relation to incoming flies; it feels easier to just place webs randomly and hope for the best, as trying to get the web in the path of an approaching fly seems more hit than miss. Either way, neat project!