Bees have a natural defensive reaction when detecting carbon dioxide, in which they exit the hive and ready themselves for a defensive attack. Carbon dioxide would signify an intruding animal (and its breath). So, why do they react the exact opposite way when they sense smoke? They retreat into the hive and ready themselves for a relocation; a retreat. If there is a high concentration of CO2 being emitted by the flame, what is the difference in the composition of gases to make them respond differently?