Honey bees play a significant role in ecosystems through pollination. Their colonies depend on maintaining a stable internal hive temperature. This temperature regulation is a complex process, involving coordinated behaviors that allow the colony to thrive. Understanding how honey bees manage temperature provides insight into their adaptability and the challenges they face in changing environments.
Understanding Optimal Hive Temperature
Honey bee colonies maintain a specific temperature range within their hive, particularly in the brood nest where eggs, larvae, and pupae develop. The ideal temperature for brood development is 93-97°F (33-36°C). Deviations outside this range can negatively affect developing bees and influence adult bee physiology and behavior.
Temperatures above this range pose significant problems. If the nest temperature rises above 99°F (37.2°C), brood can die. Sustained exposure above 100°F (37.8°C) pushes bees beyond their ability to regulate. At 104°F (40°C), the wax comb can soften and collapse, leading to severe damage.
How Honey Bees Regulate Hive Temperature
Honey bees employ several collective behaviors to cool their hive. One method involves fanning, where worker bees line up at the hive entrance and use their wings to draw hot air out, allowing cooler air to enter. Bees also fan inside the hive, directing air currents to dissipate heat and evaporate moisture.
Another cooling strategy involves water collection and evaporation. Water-foraging bees collect water, spreading droplets on combs or in empty cells. Other bees then fan their wings over these droplets, causing the water to evaporate. This evaporative cooling functions similarly to an air conditioning system.
When external temperatures are high, bees may gather on the outside of the hive entrance, a behavior known as bearding. This reduces bee density inside, minimizing heat buildup. Some bearding bees also fan, assisting in drawing cooler air into the hive. These coordinated efforts allow the colony to collectively regulate its internal climate.
Consequences of Overheating for Honey Bee Colonies
When hive temperatures exceed the bees’ ability to regulate, severe consequences impact colony health and survival. Overheating directly stresses adult bees, increasing their metabolic demands and potentially impairing their immune function. Prolonged heat stress can lead to dehydration and reduced foraging activity, making them more susceptible to diseases and pests.
Developing brood (eggs, larvae, and pupae) are sensitive to high temperatures. Pupal survival drops to zero if incubation temperatures reach 100.4°F (38°C). Exposure to even slightly elevated temperatures, such as 98.6°F (37°C), can reduce the number of emerging adult bees. Overheated brood may also develop malformed wings, legs, or abdomens, or exhibit reduced longevity and altered behaviors as adults.
Extreme heat can also physically damage the hive structure itself. Wax comb, which forms the foundation of the hive and stores honey and brood, can soften and collapse at 104°F (40°C). This can lead to loss of brood and honey, further weakening the colony. Additionally, honey stored within the hive can be negatively affected; temperatures above 110°F (43.3°C) can cause honey to lose its nutritional properties, and above 140°F (60°C), enzymes and essential nutrients are lost.
Supporting Honey Bees During Hot Weather
Supporting honey bee colonies during extreme heat helps them cope with environmental stress. Ensure hives are located in areas with adequate shade, especially during the hottest parts of the day. Placing hives under deciduous trees offers summer shade while allowing sun exposure in winter. Temporary shade structures, like an umbrella or shade cloth, can also be used during heatwaves.
Proper hive ventilation is important to facilitate air circulation and heat escape. Screened bottom boards allow air to enter from below, while upper entrances or notched inner covers provide an escape route for hot air. Propping the hive lid slightly can enhance airflow. Hive stands help air circulate around all sides of the hive, including the bottom.
Ensuring a reliable water source assists bees in their cooling efforts. Honey bees require water for evaporative cooling and to dilute honey for feeding brood. Shallow dishes filled with pebbles, marbles, or floating materials provide safe landing spots for bees to drink without drowning. Placing these water sources near hives reduces the energy bees expend on foraging for water, allowing them to focus on other colony tasks.