Just over one third of bees died last winter: 33.8%. The year before that was 29% and three years ago 35.8% of colonies died.
These are managed colonies and many or most are probably treated for various diseases. If you lose a third of your colonies after treating them, you waste the treatment cost as well as the value of the bees.
How serious are these statistics?
1. Some mortality is normal and acceptable. I don't know what's acceptable, but despite a beekeeper's best efforts, most hives will swarm at least once a year. (My hives swarm somewhere between 1.5 and 2 times a year.) If all colonies survived the winter, we'd be over run with bees in ten years.
2. The survey includes people with 5+ hives. The number of beekeepers with less than 5 has increased in all three years.
3. This number doesn't count wild colonies.
4. These losses aren't cumulative. The losses are replaced every spring and summer through swarming and swarm preventive splits.
The total number of colonies every year may be somewhere in this article and I missed it. That's probably an important number.
Anyways, I lost 1/6 of my colonies, or 16.7%, about half the national average and I didn't waste time and money on medications.
I expect more summer deaths and unless I have time to make splits and add supers, I'll probably have lots of swarms to catch again this spring and summer.