Green fly in my greenhouse already!

Just thought it worth mentioning that as I am reaching the end of my tomato growing and still have chillies waiting to bear fruit, this year I planted lots of marigolds and nasturtiums around my tunnel and thankfully no green fly, white fly or any other of these nasties, I still have them growing, but I did take out a number of nasturtiums that has started going to seed and I wanted to plant my winter spuds.