Righty, my detective work is done for the day. Best combination so far is:
1 Mashed banana, with TWO big pinches of bakers yeast stirred in, not just on surface.
Spread along the bottom of a clean cricket box, put mesh fine enough for only fruit flys and smaller to get through, many wasps tried
.
Place amongst tall grass/nettles.
Walk upto it in a few hours and simply put the lid on it, nice and quickly. Pick it up and have a look, plenty of little flys for feeding, or starting a culture, already got a few eggs in there. Have been gathering them all evening and it's really not that tricky to manage them just because they can still fly. The nymphs need to put in a little extra effort to catch them, but then I guess that's why they call it natural selection. Have seen a couple that have had trouble even managing a blackfly/aphid, yet the others are fine with these flys. Also, one nymph that caught a black fly, then didnt know what to do with it. The ***** has still got it in his 'hand' and its been over an hour, the blackfly is still waving its legs about.
Anyway, figured I might as well say what worked for me...
Dave