The bird swooping in makes it a little more suspenseful! I would play into that mechanic more and make it more random or something as it's a little too easy right now to send out the collectors until you hear the warning noise. I would probably also speed up everything as collecting flies takes too long and there's no goal. The loop is too limited, in my opinion, for it to be an infinite goal. Maybe would be better if there was a specific collection goal to progress to the next level or something along those lines.