flies are at the top of the food chain
they fly around (lol) and bump into walls, causing a very annoying and loud noise. they do this until any hooman dies, drops food, or straight up murders them. they want to end their suffering, so they do it by taking it off their mind by eating and messing with hoomans. messing with the humans actually drives them insane, causing them to have anxiety about THAT ANNOYING NOISE WHEN THEY HIT THE WALL!!! And because of anxiety this can sometimes cause the noise to kill the human they choose.
then they eat
they also do this for their children so that they can learn to kill as well. it sometimes takes years for the flies to actually kill…

they also have anxiety bc noises and try to not die but then die anyway cause anxiety. this may or may not make sense.