There have been many talks and information lately concerning the use of chemicals from beekeepers. Maryann Frazier from Penn State has looked at many comb samples from CCD hives. The contamination levels for some chemicals, and especially those used by beekeepers, has been extremely high. I recently tested one of my yards for chemicals. It showed many things in the results, but one of the items I want to point out was three chemicals were being brought into the hives by foraging bees. And although no chemicals of a beekeeper source was found, the bees were no doubt dragging in chemicals from down the road. Chemicals each individually, may pose little harm. But once they combine with additional chemicals, often the outcome is a deadly concoction. So one of the items that all beekeepers should do is practice comb rotation. In nature, comb is rotated out naturally as hives die, and the wax moths do their calling. 20 and 30 year comb just does not exist in nature. You may think your hives are clean due to the fact you do not use chemicals. But unless you are isolated on some island, your bees will come in contact with chemicals. They will bring it into the hive. It will build up in higher and higher levels within the wax, where your next generation of bees are being raised. To me, clean wax is one of the vital parts in keeping bees healthy. And comb rotation is part of that plan.