Tomato white fly.
I have a fruit cage in which I grow tomatoes, courgettes, cucumber aubergine and basil. This year more than last I have white fly in plague proportions. If I brush past a plant literally hundreds of insects fly up. The leaves are beginning to lose their greenness and have whitish spots as well. The cucumber and courgettes are particularly badly affected. I have seen a few praying mantis, but they would have to be in greater number to do any good. Does anyone have a non chemical control?