By chance I met an "old timer" in a pub some time ago and we got talking about growing veg. The conversation got round to cabbage butterfly and he told me how you can deter them.
Use any brassica leaves. Soak them in a water butt, dust bin... and let them rot down. Water using this very smelly and I mean smelly water over the leaves. Deter! I now have no problem with the pesky things. Nooooo this foul smelling mixture does not impart on your veg. How does it work? Well I think the butterfly is fooled into thinking the plant is dead.
Give it a try. Works for me
