Why Do Bees Die in Winter?

Why Do Bees Die in Winter? Understanding Winter Bee Losses and How to Overwinter Bees Successfully

https://www.youtube.com/watch?v=BXO34bvJZkI

As winter approaches, beekeepers everywhere brace themselves for the harsh realities of the season. The cold months can be particularly unforgiving for bee colonies, leading to significant losses. Understanding why bees die in winter is crucial for any beekeeper looking to improve their management practices and ensure the survival of their hives.

In this comprehensive guide, we will explore the various reasons for winter bee die-offs and provide actionable strategies to help you successfully overwinter your bees. Why do bees die in winter? Let's find out...

Why do bees die in winter? There are LOTS of reasons why...

The Importance of the Queen Bee

The queen bee is the heart of the colony, and her health directly impacts the survival of the hive. A failing queen can lead to a cascade of problems that ultimately result in the death of the colony. Here are some common issues related to queen health:

Poor Mating: If the queen is not properly mated during her nuptial flights, she may become a "drone-laying queen," producing only male drones instead of female worker bees. This can lead to a rapid decline in the colony's population.

Supersedure Failures: Bees may attempt to replace an aging or failing queen by raising a new one. If the new queen fails to mate successfully, the colony is left without a viable queen, leading to further decline.

Age-Related Decline: As queens age, their ability to fertilise eggs diminishes. An older queen may run out of sperm, resulting in a shift to drone-laying, which can spell disaster for the colony.

To mitigate queen-related issues, it is essential to:

• Conduct health checks in late summer (August/September) to assess queen performance.

• Replace queens every 1-2 years to maintain a healthy, productive hive.

• Avoid late-season inspections that could inadvertently harm the queen.

Need to requeen before winter? Check out our guide HERE - https://www.blackmountainhoney.co.uk/guides/how-to-requeen-a-beehive

Ensure your colony has a healthy queen to avoid the bees dying in winter

Starvation: A Silent Killer

Starvation is another leading cause of winter bee losses. Even if a colony appears strong going into winter, they may not have sufficient food stores to last through the cold months. Starvation can occur in two primary ways:

Insufficient Food Stores: If bees do not have enough honey and pollen reserves before winter, they will run out of food and perish.

Inaccessible Food: Even if food is present, bees may not be able to access it if it is stored too far from the cluster. As temperatures drop, bees cluster together for warmth, making it difficult to reach food stored at the edges of the hive.

To prevent starvation, consider the following strategies:

• Feed bees supplemental sugar syrup and pollen in late summer/early fall to build up their stores.

• Regularly "heft" the hives to check their weight and add more food as needed.

• Place a large slab of fondant directly on top of the cluster IF the the bees need it

Bees can die in winter (or at any time) through starvation

Varroa Mite Infestations: The Slow Threat

Varroa mites are one of the most significant threats to bee colonies worldwide. These parasitic mites feed on the bees and can transmit deadly viruses, weakening the entire colony. If varroa levels become too high, the colony may not survive the winter.

High varroa loads can lead to absconding, where bees abandon the hive entirely, leaving no survivors. To combat varroa, it is crucial to:

• Regularly monitor mite levels and treat infestations promptly.

• Use effective treatments such as miticide strips, organic acids, or introducing Varroa Sensitive Hygiene (VSH) bees.

• Implement integrated pest management (IPM) strategies to keep mite populations in check.

Read more on Varroa HERE - https://www.blackmountainhoney.co.uk/post/varroa-destructor-mastering-the-mite-menace

Your colony may look ok, but unless you keep on top of varroa, they will eventually kill your colony or make them abscond

Disease Management: Dysentery and Nosema

Winter can also exacerbate diseases within the hive, leading to further losses. Dysentery, characterised by bees having diarrhoea, can be a sign of poor hive health. Nosema, a fungal infection, can shorten the lifespan of individual bees and weaken the colony. The two are often interconnected but no always so.

To manage diseases effectively, consider the following:

• Practice good hive hygiene by cleaning and disinfecting equipment regularly.

• Isolate any colonies showing signs of disease to prevent spread.

• Use registered treatments like Hive Alive to manage Nosema and improve overall hive health.

Dysentery can be normal but it can also be a sign of Nosema

Moisture Control: The Hidden Danger

Excess moisture in the hive can be detrimental to bee survival. While bees can tolerate cold temperatures, the combination of cold and damp can be deadly. Condensation can drip onto the cluster, chilling the bees and leading to death. Cold and damp hives also make it very difficult for the bees to maintain temperature and will result in starvation much quicker than a dry, well insulated hive.

To manage moisture levels, consider these strategies:

• Ensure the roof/crown board are very well insulated

• Ensure the walls are insulated slightly less than the roof/crown board

• Use an open mesh floor to allow excess moisture to escape from the hive

An insulated poly ashforth feeder is a great investment for your bees

Colony Size and Hive Fit

The size of the colony relative to the hive box is crucial for winter survival. Small, weak colonies are more vulnerable to winter losses than larger, robust ones. If a colony is too small for the size of the hive, they may struggle to maintain the necessary cluster size and temperature.

To optimise colony size and hive fit, consider:

• Matching the colony size to the hive box size going into winter.

• Using insulation to help small colonies retain heat.

• Consolidating weak colonies into smaller, more manageable boxes.

Make the bees fit the box to get them through the winter

Avoiding Beekeeper Errors

Many winter bee losses can be attributed to simple mistakes made by beekeepers. Common errors include:

• Forgetting to open hive entrances, trapping bees inside.

• Failing to install mouse guards, allowing rodents to invade the hive.

• Conducting late-season inspections that accidentally harm the queen.

To avoid these pitfalls, it is essential to stay vigilant and double-check all aspects of hive management as winter approaches.

There is nothing worse than finding your bees have died over winter and it was a beekeeper error!

Proven Strategies for Successful Overwintering

Now that we have explored the main reasons for winter bee losses, let's discuss some proven strategies to help your colonies survive the cold months:

1. Assess and Prepare Colonies in Late Summer

Late summer (August/September) is the ideal time to evaluate your colonies and prepare them for winter. This includes:

• Checking queen health and mating status.

• Ensuring adequate honey and pollen stores.

• Treating for varroa mites if needed.

• Consolidating weak colonies into smaller boxes.

2. Provide Supplemental Feeding

Even if your colonies appear strong, they may still need extra food to get through winter. Consider:

• Feeding supplemental sugar syrup and pollen in late summer/early fall.

• Placing large slabs of fondant directly on top of the cluster in late fall/winter IF NEEDED.

• Regularly hefting hives to check their weight and adding more food as needed.

Check out our latest blog on feeding HERE - https://www.blackmountainhoney.co.uk/post/can-i-feed-my-bees-too-much

Feed your bees well in the build up to winter

3. Optimise Hive Setup and Insulation

The configuration and insulation of your hives can significantly impact winter survival. Consider:

• Matching the colony size to the hive box size.

• Using high-quality insulation materials like polystyrene.

• Avoiding tunnel entrances that allow cold air to flow through the hive.

• Insulating above the winter cluster

4. Monitor and Treat for Pests/Diseases

Staying on top of pest and disease management is critical for overwintering success. Consider:

• Regularly monitoring varroa mite levels and treating infestations.

• Using registered treatments like Hive Alive to manage nosema.

• Practicing good hive hygiene and isolating any sick colonies.

  
  

Always treat your bees for varroa!

5. Avoid Late-Season Disturbances

Finally, avoid unnecessary late-season inspections or disturbances to the hive. This includes:

• Checking for the queen in October/November.

• Closing off hive entrances by accident.

• Allowing mice or other pests to invade.

Start winter preparation in the late summer

Conclusion

Overwintering bees is one of the most significant challenges beekeepers face, but with the right knowledge and preparation, you can dramatically improve your colony survival rates. By understanding the common causes of winter bee die-offs, from failing queens to varroa infestations to simple beekeeper error, you can take proactive steps to give your hives the best chance at making it through the cold months.

Remember, the key is to get your colonies in tip-top shape before winter arrives. Assess their health, ensure they have ample food and insulation, and stay vigilant for any signs of trouble. With a little extra care and attention, you can help your bees weather the winter storm and emerge strong and healthy in the spring.

For more beekeeping tips, advice, and resources, be sure to check out Black Mountain Honey. We offer a wealth of information on queen rearing, disease management, honey extraction, and much more. If you're in the market for high-quality nucleus colonies or queen bees, our online store is the perfect place to shop.

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Here's to a successful overwintering season and a thriving bee population in the year to come!