I have a new greenhouse and I have had a particularly unpleasant problem which I did not expect to have to deal with. Lots, and I mean LOTS, of flies come into the GH and can't find their way out. They eventually die and create a nasty mess all over. It's really rather horrid, not least for the insects, which includes bees, butterflies and moths.
Does anyone have any bright ideas of what to do. Fly paper wouldn't cope with the large numbers and the design of the GH ( square with a high apex) doesn't allow their escape.