Yes I agree, supplementary is the operative word here. I feed according to their needs so to speak. If I have food left over for two or three nights running, I reduce the amount. If all gone over the same period then I increase the amount that they have. Also I am not so keen at cutting the grass like I used to, that will attract more beetles and things into the garden that are more natural for them to eat. Just small changes can make a big difference.