I think it better to look carefully at the development of new bees with in the hive. Fact that they do not find dead bees in the hive is reasonable good indication that few die there. Normally, in summer the are out working break a wing etc. and die. Unlike many animals, bees can not repair any damage the sustain. Again this is consistent with my POV that bees are only the cells of the living hive organism. Our cells are dying all the time and like bees, they just get replaced. I suspect, if GM toxins built into each cell are causing the CCD problem, including the pollen, which is the only protein source for making new bees, then it is like Thalidomide - I.e. causing fatal gestations defects, but harmless to the adult bees.