Dearth can spell death for weak colonies, but for the healthy colonies in your apiary, it's just another time of year. As a beekeeper, you may need to take action to help your bees, or you may just need to watch and wait as they eat some of their stored spring honey to keep them healthy until the dearth ends. Read on to learn how to tell if bees are in a dearth and the best ways to support your colonies during times of low or no nectar flow.
Dearth is any period of time when no significant amount of nectar is coming into your hives because no notable nectar-producing plants in the area are blooming. A dearth (an absence) of nectar means that your hungry bees will have to eat stored honey or syrup from a feeder to sustain themselves. The opposite of a dearth, a honey flow or nectar flow, is when one or more plants are producing plentiful nectar that the bees can dehydrate and cure into large amounts of honey.
Plants make nectar as an attractive reward for the pollinating insects that help the plants reproduce. As bees and other insects collect nectar, plant pollen sticks to their bodies and is carried from flower to flower, contributing to seed production. In the spring or the fall, rainwater and groundwater are often plentiful, so the cost of making nectar is simply adding a bit of sugar to the water in each flower's nectary.
However, during a hot dry summer, water is much dearer to plants — they don't want to lose it to evaporation or offer it to pollinating insects. Most plants won’t bloom in the hottest and driest months, which closes the nectar buffet for local pollinators. Because many plants only bloom for a week or two each year, some days — or weeks, or even months — may have very few flowers available.
In short, it depends: There is no specific timing regarding when dearth starts and stops. We can offer some notes about when the midsummer dearth starts here in the lower Adirondacks region, but our seasons are not necessarily the same as yours, and neither are our plant species.
Usually, we see a few months of relatively minor dearth in our apiaries after the May to June nectar flow ends, and before the first goldenrod species begin blooming in August. Our bees are still bringing in nectar from various summer plants, but aren’t making very much honey. Fall is much more boom-and-bust: If there is blooming goldenrod the bees may bring home gallons of nectar to start processing, but when the goldenrod is finished the bees have almost no other foraging opportunities. This is when we sometimes start to see large hives robbing honey from weak ones as everyone prepares for winter.
While you may learn about the typical dearth dates in your local beekeeping association meetings, remember that your apiary might be on a cold mountain with a different blooming cycle, or maybe your bees are surrounded by land that lacks an important nectar source that other people’s bees have access to. Even when you've figured out your local nectar flow patterns, you can't mark your dearths down on a calendar. Each year the weather is different — especially in recent years. That means a plant that was still blooming last July might be completely spent by mid-June this year.
The dearth starts when the local plants say it does, so pay attention during hive inspections to see when nectar stops coming in each year. As you drive around town, notice which plants have blooming flowers on them and which plants have wilted flowers, indicating that their bloom is over for the year. Watching local plants can help you figure out if things are progressing faster or slower than they did in previous years.
Evaluating your hives will provide important clues as to whether your bees are in a dearth. With no new nectar coming in, your bees will stop making honey or nutritionally expensive wax comb to focus on keeping the colony alive and healthy. Some colonies will reduce brood rearing during dearth, especially if they have only small stores of pollen and honey to feed the larvae.
The main signs of a nectar dearth are:
Dearth can range from extreme to relatively mild. In some regions, the period of "dearth" is just the time between the plentiful nectar flow from Plant Species 1 and the flow from Plant Species 2. During such gaps, nectar is still available to the bees, but it may not be very much and is coming from many different plants. Such minor dearths are something to be monitored — but are rarely cause for concern.
On the other hand, a severe, or complete, dearth is when there are essentially no flowering plants blooming in the foraging range of the hive. Bees will search further and further looking for food sources, but in some places like deserts, there are simply no flowers to be had for miles and miles around at some times of the year.
The more severe the dearth, the more likely the bees will require supplemental feeding. Talking to other nearby beekeepers about how serious the local dearth is will let you plan what you’ll do to keep your bees healthy.
Keeping your bees happy and healthy during dearth depends on preparation before dearth begins, and observation and action during nectar shortages. For more information and tips for helping your colonies thrive year-round, explore our Beekeeping Guide.