I have a problem with greenfly in my greenhouse. I have tried several sprays both organic and commercial chemicals but to no avail. I was hoping to get some advice on doing something over the winter-the only problem is that the greenhouse is never empty. There are winter lettuces and some permanent residents like lemon and orange trees.
The trick is to observe the arrivals and to use a control product in time before the big build-up of numbers take place.
Biological control methods are used commercially but these are difficult to manage successfully in a small greenhouse.