They won't move them until the young have all finished growing... probably another 2-3 weeks, and if you try to get rid of them another way you may find yourself with a very hefty fine.... have patience and get a good strong tarp....

St Swithun's day (15th July) was fairly dry so you might be OK (40 days of fine weather allegedly, if old legends are anything to go by... strangely enough this one is more often right than not - shifting weather patterns settle down towards the middle of July, so we get a fairly constant weather pattern. It usually breaks up 6-7 weeks later, just around August Bank Holiday) with the weather.

But as someone above stated, they are better than any bug spray at catching mosquitoes and other nasty biting things with wings (cue Monty Python's "All things dull and ugly").

Good luck with them, and have a jolly holiday anyway!

LTS