I do understand what you mean about the flies. It's just in pollination ecology, people talk about bees as being more intelligent and choosy than flies in terms of the flowers they visit. The euglossine bees can also be generalists, however, in the sense that they can 'capture' pollinia of multiple orchid species on the same fly, stuck however on different parts of their body, due to the specific morphologies/anatomies of different species. I think the central issue is that the Paph species are largely allopatric in distribution, and so different fly species are not much involved in 'choices', other than what can actually fit through the floral 'devices' to effect pollination. 'Sophisticated' attracting systems such as the distinct staminodia of Paph rothschildianum may well separate its pollination from other species that are more-or-less sympatric, however (such as P. dayanum; though these plants aren't really sympatric in the sense that they grow directly next to P. rothschildianum populations!). I think, though, that if you look at most Paphs, they exist in substantial allopatry, and the fly species probably don't make much of a difference other than mechanical possibility due to their size and shape, etc. But, I natter on, and probably contradict myself in places above... Just my 2 cents again. Specificity seems to be a matter of defition. All best, vic.