I thought that this had been figured out already years ago. The honey bees have been going away for quite a few years now. I heard that it was the mites that kill them. Nature has counter acted with a strain of lady bugs that eat the mites. It will take some time for things to turn around. Maybe the honey bees will never come back to the numbers we all remember. I have a lot of bumble bees doing the work on my fruit trees. There are no regular honey bees around here and there hasn't been for years.