It was an unusual season here in Michigan, and I know that this is true elsewhere. Here a few of many observations I made:
Spring came early
Very early spring weather, following a relatively mild winter, produced some enormously strong colonies in March and April. After a very warm period in March we had a more seasonal period. This grew colonies quickly. The milder winter means that colonies were in pretty good shape in terms of their population.
It seems that bees swarmed every month this year, from March to October—not every colony every month, but it was always some colony’s turn to swarm. New colonies swarmed, packages, nucs, and nucs from nucs. As a result of the warm March and then confinement in April, colonies were under a strong stimulus to swarm, and this urge continued well into June. Then the weather became very hot, over 100 degrees F. for several days—the colonies were put into another set of stresses and stimuli. I made up five-frame nucs in June and took off for Alaska, only to return to find that many of them had swarmed as evidenced by swarm cells, emerged and un-emerged. The virgin queens we introduced had mated, laid the nuc up heavily, and then swarmed. There are swarm colonies around the farm with yellow-marked queens heading the colony. I suspect there are a huge number of purchased and home-reared queens that are in bee trees and related structures right now. We certainly did a great job of repopulating the bee trees this season.
Drought and nectar flows
Many newer beekeepers have asked me about the dry and hot weather and its impact on honey production. They assumed that this would end any nectar flow that was underway, and/or prevent one from happening. Yet, most of the beekeepers I consulted say they had a big honey crop this year, pulling several gallons from each hive once or even twice during the season. Now, I must be clear, we had a moderate drought for part of the summer, not the season-long, waterless conditions others have experienced in other parts of North America. We had rainfall between periods of hot, dry weather. Perhaps this is the perfect set of conditions for nectar production.
For a plant to produce nectar in its flowers, it must be exposed to sunlight for most of the day. This sets up the physiological process to convert solar energy into sugar, and then pump the nectar into the nectaries where it is released to reward foragers. A few past seasons were cooler and very cloudy, and the conditions for nectar production were poor. But with the hot and sunny weather interspersed with rain showers, we had plants that were growing well but perhaps a bit stressed, which seems to stimulate it to allocate more plant resources toward production of nectar.
To simplify, given warm weather, sunlight stimulates nectar production in plants that are tolerant of heat, and that includes trees like black locust and basswood, as well as legumes (clover, alfalfa, birds-foot-trefoil) and herbs like spotted knapweed, goldenrod and aster.