Mine have been going strong for almost a year now. I don't think they would overpopulate. I don't know too much about them but frog people don't have problems with that. I can only really see them when I pour water in to keep the bottom layer of hydroballs in water. Then they come to the surface and tiny moving specks can be seen. I'm sure they probably just die naturally as such insects have short lifespans anyway. Then the living springtails clean up the dead ones.