After constantly seeming to have a fly or two annoying me in the house, I decided to grab a fly trap from Bunnings for $5 and stick it outside to see if that might stop them coming inside. Well, long story short, it has but it has worked so well I have thought that it might be worth taking one camping when we go and set it up 10m or so away, and just wondering if anyone else has done so.
It took a day or two too really get cranking but in the week since then it has almost filled up (about 1/2L volume at a guess) so might pay to get one started a couple of days before you head away to make sure it's cranking when you get there.
I wouldn't have guessed there would have been anywhere near the volume of flys around that have poured into it, but not sure from how far afield they are coming from either, have almost taken a morbid interest in watching them go in there and it filling up.