Bee Temperature Tolerance: What Temperature Kills Bees?

What temperatures can honey bees tolerate? Do they die when it gets too hot or cold?

The truth is that bees are very tolerant creatures and have adapted to live in extreme weather conditions around the world.

However, like almost every living thing, they too have their limits. When the temperature becomes too hot or too cold, bees will die. But what exactly are their limits?

Well, bee temperature tolerance has been found to vary across species. Honeybees that have adapted to tropical climates, for example, will have a higher tolerance to hot temperatures.

On the other hand, honeybees adapted to cooler climates are more likely to survive when the temperature becomes very cold. This is because different species of bees have evolved over time to meet the demands of their respective climates.

Beehive covered in snow

Do Bees Die When It’s Too Hot?

Bees can tolerate high temperatures for extended periods. When it becomes too hot, they produce heat shock proteins, which help protect their cells from thermal-induced stress. However, if the weather stays too hot for too long, they will suffer severe body water loss and die.

One study showed that California honeybees can survive for around 2 weeks when the temperature is kept at 35°C (95°F). However, when the temperature rises to 40°C (104°F), bees only survive for about 3 days. At 45°C (113°F), bees die in less than 24 hours.

It’s important to remember that this study kept bees at constantly high temperatures. Normally, bees are subjected to fluctuating temperatures as the weather becomes cooler at night and varies from day to day. However, it does show that extended periods of extreme heat can be fatal to honeybees.

How Do Bees Survive Hot Weather?

Bees are incredibly resilient creatures. They survive hot weather by working together to maintain the temperature of their hive, which provides them with a place to shelter from the sweltering heat.

Here are the main ways in which bees survive hot weather:

  • Fanning their wings in a coordinated pattern to increase airflow throughout the hive.
  • Placing water droplets throughout the hive before fanning their wings to evaporate the water and create a cold air current (a method similar to evaporative cooling).
  • Expanding the central cluster so that there is more space between bees, allowing for better circulation of air.
  • Partially evacuating the hive when it becomes too hot inside (known as bearding).

Where the hive is located can also help keep bees cool. In fact, in tropical climates, you can find bees nesting in the open instead of the hollow of a tree. This allows for extra ventilation throughout the colony.

Do Bees Leave The Hive In Summer?

Bees still leave the hive even when the weather is very hot. There are many flowers in bloom during warmer months and bees need to collect nectar and pollen to feed the colony.

Bees will also leave the hive in search of water, which becomes vital to their survival during hot weather. Not only do bees drink water, but they use it for evaporative cooling to keep the hive at a temperature that’s safe for brood development. That’s why it’s vital there is a source of water close to the hive.

Beehives in a field of dry grass

Do Bees Die When It’s Too Cold?

Bees are resilient to cold weather and have adapted to live in many parts of the world where the weather reaches very low temperatures.

Bees survive Winter by staying inside the hive and working together as a team to keep warm. If a single bee ventures out into the cold, though, it’s a different story.

Studies show that a honeybee will die within an hour if the temperature drops below -2°C (28°F). If the temperature is between 9-12°C (48-54°F), bees fall into a chill-coma where they can survive for up to 50 hours if they are then warmed back up to room temperature.

How Do Bees Survive Cold Weather?

Just as they do in Summer, bees use their hive in Winter as a shelter from extreme weather. This is especially important for the brood, which needs to be kept in a stable temperature range of 34°-36°C (93°-97°F) to safely grow into healthy adults.

Here’s how bees survive cold weather:

  • Vibrating their flight muscles rapidly to generate heat (because this expends a significant amount of energy, bees eat a lot of honey during Winter)
  • Clustering together to stop the heat from escaping
  • Plugging any unnecessary holes with propolis to stop heat from escaping
  • Worker bees transfer heat to the brood by pressing their bodies on top of capped honeycomb cells containing larvae or pupae, and vibrating their flight muscles to generate heat

Using these methods, bees can survive inside their hive even if the temperatures outside are below freezing.

The hive location can also help bees survive Winter, which is why wild swarms (as well as beekeepers who manage beehives) are so careful in selecting somewhere that protects the colony from the harsh weather.

Do Bees Leave The Hive In Winter?

In cold weather, bees are much less active because they are needed inside the hive to keep the colony warm. Cold weather also typically means fewer flowers in bloom, so there is less food for bees to find in Winter. Therefore, far fewer bees leave the hive in Winter.

What Temperature Do Bees Stop Flying?

According to one study, most honeybees stop flying when the temperature is below 10°C (50° F). At 16°C (60.8° F), bees become active and start to leave the hive again. Above 20°C (68° F), the number of bees flying increases significantly as more and more bees leave the hive searching for food.

Temperature not only affects the number of bees flying but also how far from the hive they fly. When the weather is cold, most bees don’t fly more than 50 meters (165 feet) away from the hive to forage for food. That’s compared to when the weather is warm, when bees will fly up to 13 kilometers (8 miles) or more if they have to in order to collect pollen and nectar.

At lower temperatures, high winds, rain and low light intensity also reduce the level of flight activity in bees. Almost no bees fly during the rain or during high winds, and fewer bees than normal fly when it is cloudy.

An apiary with dozens of beehives, all covered in snow

Summing Up Bee Temperature Tolerance

Honeybees have a strong temperature tolerance and have adapted to live in many parts of the world where there are extreme temperatures.

Despite their high degree of tolerance, a bee will die if it becomes too hot (above 45°C  or 113°F) or too cold (below -2°C or 28°F).

When the weather reaches these extremes, bees work together as a team to implement thermoregulation methods that keep the temperature inside their hive at a safe level.

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