Very odd. Farmers have been using pesticides for many, many bee generations. Why the sudden problem. Why would the bees leave, en mass, prior to dying? Why such a preponderance in winter?
Has there been a decline in crop production? If so many bees are dying there should be a corresponding drop in production. I have read nothing about that.
Two years ago we had 3 swarms in one summer. It meant that there were tons of bees zooming out of that hive during each swarm. I was pleased with the amount of bees we were getting.
Last year we had another very active hive, but didn't have one swarm. I don't feel the need to panic at this point. But it will be interesting to watch the colony this summer.