Do Bees Pant?

We often notice a bee, perhaps resting near the hive in a pool of sunlight, appearing to pant, with the abdomen pumping in and out (figure 1). So are we watching the bee getting its breath back?

Bees, like all insects do not breathe through the mouth, and indeed do not have lungs at all. They breathe through spiracles, a series of small openings along the body. The air passing through the spiracles is led into a network of tubes (tracheae) and air sacs (known as tracheal sacs) (figure 2) and ultimately to minute tracheoles (figure 3) which lead right into all parts of the body, even penetrating inside muscle cells. One of the fundamental differences between insects and vertebrates is that insects do not cany gases around in the circulation, but instead bring air directly to the tissues of the body. Vertebrates exchange gases from air to blood in the lungs binding oxygen to a carrier molecule, haemoglobin, and pumping it around the body in the circulation. However in insects the air is carried internally as a gas, throughout the body. Tracheoles take air close...