thanks pete, some good points and info....especially what you said about recognizing or anticipating a dearth. also, the author said bees don't rob in a nectar flow, well, yes and no. i have had 5 frame nucs robbed out during nectar flows, some years they don't? so, to be on the safe side, when i make up a nuc now, it gets moved. jack said it best in another thread, bees are opportunists.
robbing screens do work really well. i make my own, not like iddee's, a little different, and i use them for moving bees. iddee has a great thread here, step by step instructions for anyone that would like to make their own robber screen that also doubles for moving bees as well:
Robber Screen & Moving Screen