Honeybees. Thermogram of honeybees (Apis mellifera) on honeycomb. The colours show variations in temperature. The scale runs from blue (coldest), through red, to yellow and white (warmest). Some bees are warmer than others because they are actively generating heat by vibrating their wings. This is necessary to warm developing larvae and pupae in the brood cells. Empty cells in the honeycomb help to trap heat and are therefore a necessary part of a honeycomb's design. Thermography records the temperature of surfaces by detecting long- wavelength infrared radiation.