Armin,
For predators - I recommend a Forum-Membermeeting - keep a sufficient number of fly flaps ready and here we go!
There is a good number of excellent 'flycatchers' among them - see Forum notes - and you'll soon get
rid of your problem.
If these 'predators' will stay too long there will be a new problem concerning board and lodging.
Gerd
Gerd,
it seems I scored a own goal
I did'nt mean the two-legged kind of predators scurrying with a fishnet...
But, on the other hand, why not invite skilled 'flycatchers' for help