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How bees stay cool on hot summer days

If you've ever walked past a bee's nest on a hot summer day, you've probably been too focused avoiding getting stung, rather than stopping to wonder how all those bees stay cool. Don't worry, National Science Foundation-funded scientists have braved the stingers to ask and answer that question for you. Honey bees live in large, congested nest cavities, often in tree hollows with narrow openings. When it gets hot inside the nest, a group of bees crawl to the entrance and use their wings as fans to draw hot air out and allow cooler air to move in. The question is, how do bees self-organize into these living ventilating units? The researchers have developed a framework that explains how bees use environmental signals to collectively cluster and continuously ventilate the hive. The research team measured temperature, air flow into and out of the nest, and the position and density of bees fanning at the nest entrance. They observed that rather than spreading out across the entirety of the nest entrance, the bees clustered at the hottest areas and kept those areas, which had the highest air outflow, separate from the cooler areas with the highest air inflow. Importantly, they found that different bees had different temperature thresholds above which they would begin fanning, so that collectively they were better at responding to temperature variations.

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