A dearth in beekeeping is a period when there isn’t enough nectar available in the environment for bees to forage on. It’s essentially a food shortage, and it can last anywhere from a few weeks to several months depending on your climate and region. During a dearth, colonies shift from growth mode into survival mode, consuming their stored honey, becoming more defensive, and sometimes turning on neighboring hives to steal their food. Understanding when dearths happen and how to spot them is one of the most practical skills a beekeeper can develop.
Why Nectar Stops Flowing
Nectar is a sweet liquid that plants produce to attract pollinators, but plants treat it as a luxury. When conditions get tough, nectar production is one of the first things a plant shuts down. The main trigger is water stress. Plants constantly pull water from the soil and release it through their leaves in a process called transpiration. When soil moisture drops, the plant prioritizes its own survival over reproduction, and nectar secretion stops.
Research on squash plants found that reducing soil moisture by roughly 10% caused measurable drops in both the volume and sugar concentration of nectar. Heat and drought often work together: a stretch of hot, dry weather dries out the soil while increasing the rate at which plants lose water through their leaves. The result is that flowers may still be visible in the landscape but produce little or no nectar, which can be confusing for new beekeepers who assume blooms automatically mean food.
A shortage of nectar-producing plants is the other major cause. Between spring wildflowers finishing and fall goldenrod starting, many regions hit a gap in mid-to-late summer where very little is blooming. This “summer slump” is the most common dearth beekeepers deal with, though dearths can also occur during drought at any time of year, or during winter when plants go dormant entirely.
How Bees Behave During a Dearth
The personality of a colony changes noticeably when nectar stops coming in. A hive that was calm and easy to inspect a month ago may suddenly sting more readily during routine checks. Bees that aren’t collecting nectar have less to do and more to protect, so they become defensive. If you’ve noticed your previously gentle colony getting testy for no obvious reason, a dearth is one of the first things to consider.
Foraging patterns shift too. Bees start flying farther from the hive and visiting flowers they’d normally ignore. You might see honeybees on plants they wouldn’t touch during a strong nectar flow, simply because they’re desperate for anything producing even trace amounts of sugar. Foraging activity outside the hive often drops overall since there’s less to find, and you’ll notice fewer bees coming and going from the entrance.
The most dangerous behavioral change is robbing. When foragers can’t find nectar in the field, they sometimes locate a weaker colony and steal its honey instead. Robbing can escalate into a full-blown frenzy where hundreds or thousands of bees from stronger hives overwhelm a weaker one, draining its stores and sometimes killing its bees in the process. This is one of the biggest risks beekeepers face during a dearth, and it can cascade through an apiary quickly.
What Happens Inside the Hive
Without incoming nectar, the colony starts consuming its honey reserves. Hive weight drops steadily as bees eat through their stores. Research tracking daily hive weight found that colonies in resource-poor environments lose more weight than they gain each day, since foragers burn energy searching for food but come back with little to show for it.
The queen responds by slowing or stopping egg laying. Workers feed her less, her abdomen shrinks, and the brood nest contracts. In late summer and fall, bees often backfill portions of the brood nest with honey, physically restricting the space available for the queen to lay. This is a deliberate survival strategy: fewer mouths to feed means existing stores last longer. The colony is essentially downsizing its workforce to match the available food supply.
Drones get hit hardest. Since drones don’t forage or do hive work, they become a pure drain on resources during a dearth. Workers begin dragging them out of the hive, sometimes physically carrying uncooperative drones to the entrance and pushing them off the landing board. Drone eviction is a reliable sign that the colony is tightening its belt.
How to Spot a Dearth
Several signs during hive inspections point to a dearth in progress:
- Declining honey stores. Frames that were heavy with capped honey a few weeks ago are noticeably lighter or partially empty.
- Less foraging traffic. Fewer bees are leaving and returning to the hive entrance compared to peak nectar flow.
- No fresh white wax. During a nectar flow, bees build new comb with bright white wax. When nectar stops, new construction stops.
- Increased aggression. The colony is noticeably more defensive during inspections or when you walk near the hive.
- Bees clustered inside. Rather than spreading across multiple boxes, bees may be huddled together conserving energy.
A hive scale is the most objective tool. If you’re tracking weight and see a consistent downward trend over several days, the colony is consuming more than it’s bringing in.
Protecting Hives From Robbing
Preventing robbing is the top priority during a dearth. The two main tools are entrance reducers and robbing screens, and they serve different purposes.
Entrance reducers are your first line of defense. They narrow the hive opening so fewer guard bees can effectively patrol it. Install them before trouble starts, especially on weaker colonies, nucs, or hives with small populations. A colony with a small workforce simply can’t defend a full-width entrance against a determined robbing force.
Robbing screens are the escalation tool. If robbing has already started, a simple entrance reducer often isn’t enough. Robbing screens work by separating the visible entrance from the actual way into the hive. The colony’s own bees learn the alternate route quickly, but invaders keep trying to push through the decoy entrance and eventually give up. Deploy a robbing screen immediately if you see frantic, fighting bees at a hive entrance.
One important rule: never open-feed sugar syrup during a dearth. Setting out a communal feeder in the apiary teaches bees that easy food is available nearby, which triggers and reinforces robbing behavior. Any supplemental feeding should happen inside individual hives using frame feeders or similar devices that only that colony can access.
Feeding Through a Dearth
Supplemental feeding can bridge a dearth, but the type of syrup matters depending on when and why you’re feeding. A 1:1 ratio of sugar to water by weight mimics a light nectar flow. Bees tend to consume it quickly rather than store it, which makes it useful for stimulating brood rearing during a mid-season dearth when you want the colony to keep growing. Frame feeders placed inside the hive are the recommended method for mid-season supplementation.
A 2:1 ratio of sugar to water (70% sugar content) is thicker and designed for storage. This is what you’d feed in late summer or fall when the goal is building up honey reserves for winter. The lower moisture content means bees can process and cap it faster, which matters when cold weather is approaching and they need sealed stores to survive on.
Pollen or pollen substitutes can be just as important as sugar syrup. The last rounds of brood reared in autumn produce the long-lived “winter bees” that will carry the colony through to spring. Without adequate protein from pollen, colonies can’t rear healthy brood during this critical window. Experienced beekeepers in areas with late-summer dearths often feed high-quality pollen substitute to keep brood rearing strong heading into fall, even when natural pollen is scarce.
Summer Dearth vs. Winter Dormancy
Not all dearths are the same. A summer dearth is a temporary gap in an otherwise active season. Colonies are still raising brood, foragers are still flying, and the queen may still be laying, just at a reduced rate. The main risks are robbing and starvation of colonies that didn’t build up enough stores during the spring flow.
Winter dormancy in cold climates is a different situation entirely. Pollen becomes scarce or absent, the queen stops laying, and the colony forms a tight cluster to conserve heat. There’s no foraging to manage and no robbing pressure from other colonies. The challenge is purely about having enough stored honey to last until spring. In subtropical climates, the pattern can actually reverse: colonies may restart brood rearing during winter when seasonal rains trigger new plant growth after a dry summer dearth.
Regional variation means there’s no universal dearth calendar. In the arid western United States, late summer dearths are severe enough that some commercial beekeepers truck their hives to other states for better forage. In the Southeast, the gap between spring and fall flows may be shorter but still significant. Learning your local nectar flow pattern, including when the gaps typically fall, is one of the most valuable things you can do as a beekeeper in any region.