In the hottest part of summer nectar and pollen flows can slow down substantially, or even stop completely – a situation called a nectar dearth, or simply “the dearth.” Many new beekeepers are unaware of the dearth and the challenges it presents. As a result, their colonies emerge from the dearth weakened and less likely to survive the coming winter.
The first problem is that of starvation. Colonies that have been fed in the spring will often have huge populations, both from the feeding and also because they have been supered up with queen excluders so the vast majority of their honey stores are outside of the brood nest, giving the queens plenty of room to lay their brood. The huge population is an asset when it comes to nectar collection; supers fill fast when the nectar is abundant. But by the middle of July, most beekeepers have taken the supers full of honey for themselves. This is not a problem if the nectar is flowing, but when the dearth hits it becomes a crisis. A huge population, perhaps more than 80,000 honeybees, remains in the colony with little in the way of honey stores. It takes a lot of energy to sustain a large population and it does not take long for the little honey stored in the brood chambers to be depleted. If the dearth is severe and especially if it is prolonged, starvation can ensue. That’s right: in the middle of the summer, hives can starve.
Another result of the dearth is a reduction or cessation in brood production. The queen’s egg laying is regulated by the nectar and pollen coming into the hive. When food is abundant, the queen will lay thousands of eggs each day. But as the pollen and nectar flow slows, the queen’s brood production slows or even stops. It is common to open a hive during the dearth, only to find capped brood with no eggs or larvae. Because she is not laying, the queen’s abdomen may be slimmer than usual and novice beekeepers may have difficulty finding her if she is unmarked, leading them to think the hive is suddenly queenless.
It doesn’t take much imagination to realize that the sudden lack of pollen and nectar, coupled with little stored honey and little or no new brood results in a rapid population decline. This decline, in and of itself, is usually not the main problem. When the dearth ends, the queen will resume laying and the population will increase, although seldom to its pre-dearth levels.
The problems that do arise are actually side effects of the population decline. Among these problems, robbing is the most severe. Strong colonies can begin to rob weaker ones and colonies that are especially weak can even be robbed by other insects, such as yellow jackets or wasps. Once robbing begins, it is extremely difficult to stop and usually results in the death of the hive being robbed.
Another problem during the dearth is wax moths. By mid-summer, the nest has expanded but the sudden decline in population leaves the remaining workers with too much space to defend. A strong colony can keep wax moths at bay but a weaker one can quickly be overwhelmed, especially if the hive is too large for them to defend.
The final problem is that once the dearth ends, there may be a sudden strong nectar flow. But since the population is low and it takes time to build it back up, the population may be too small to really take advantage of a strong nectar flow. This results in lower honey stores in the colony and can decrease its odds of overwintering successfully.
For some beekeepers, the answer is just to let things ride, letting the bees do what they do. There is nothing wrong with this outlook, but new beekeepers who have this laissez-faire philosophy need to realize that a corollary is less honey for themselves and poorer chances of overwintering for the colony. Another approach to the dearth is to feed. The advantage of feeding is that the population can remain high due to the artificial pollen and nectar flow created by feeding sugar syrup and a pollen patty. The greater population will be more effective at keeping wax moths at bay. Furthermore, it will be less susceptible to robbing and less prone to rob other colonies. And when the dearth ends, the colony will be better able to take advantage of a strong fall nectar flow, resulting in more honey for the beekeeper as well as more honey stores in the colony itself, improving the odds of successful overwintering.