Here in the northern hemisphere, your calendar may tell you it’s the first day of winter, but from the bee’s perspective, it’s actually the first day of spring. Like many plants and animals, bees are highly affected by changes in day length. Immediately after the winter solstice, when the hours of daily sunlight start to increase, the colony begins to change and bee season begins.
Within a few days of the solstice, the worker bees slowly begin to raise the temperature of the brood nest from a cool resting temperature of 70-75° F (21-24°C) to the brood rearing temperature of about 95°F (35°C). This increase in warmth spurs the queen to lay eggs. She will build a small brood nest and gradually, over the course of many weeks, increase the size of her nest. If all goes well, the hive population will explode with the first warm weather of the new year.
Food is the key for bee season
But the transition is not easy. Maintaining a warmer nest requires more food just when food stores are getting low. If food is too scarce, brood production will be held in check. If food is readily available, the hive will bloom along with the flowers.
As most beekeepers know, the hardest time to keep a hive alive is during early spring when the number of bees may far exceed the available food—especially when a cold snap follows a stretch of balmy weather.
Summer solstice is the signal to stop
Although we seldom think of it, the summer solstice (the first day of summer) marks the beginning of the end of bee season. Think of the old adage:
A swarm of bees in May is worth a load of hay;
A swarm of bees in June is worth a silver spoon;
A swarm of bees in July isn’t worth a fly.
The poem reminds us that a swarm captured in May or June has the potential of surviving and storing enough food for winter, but a later swarm—say one captured in July—has a much lower chance of succeeding. So what’s the difference? What happens between June and July?
Winter begins in June
The answer, of course, is that the summer solstice happens between June and July—somewhere around June 20-21. At the summer solstice the hours of sunlight begin getting shorter and the bees start making preparations for winter. Brood production drops, hive populations taper off, and winter survival outranks reproduction as the number one priority. Most often a late swarm cannot maintain the number of bees needed to prepare for winter because brood production is decreasing . . . the length of daylight has the last word.
The take home message for beekeepers is this: forget the labels we put on our seasons, forget all the business of changing our clocks to fit our notions of day and night, and instead watch the sun. In the end, it is the change in daylight hours that governs the life cycle of our honey bees.