The Bumblebee That Turns Itself Into a Living Furnace How does a cold-blooded insect fly in freezing temperatures that ground almost every other bee? By becoming a living heater. Bumblebees can actively warm their own bodies by shivering their powerful flight muscles — the same muscles they use to fly, but decoupled from wing movement. This generates heat internally, raising their thoracic temperature to around 30–35 °C, even when the surrounding air is close to freezing. Before take-off, a bumb