At first glance, a moth might not have so much in common with a jet. One slices through air decisively, whereas the other flutters about, visiting blooms and vegetation, but both are powered by a powerful current of air drawn in through the front and expelled out the back. Hawkmoths depend on this air flowing through the air tubules distributed throughout their bodies to provide sufficient oxygen to fuel the immense muscles that power flight. But it wasn't clear how air was drawn into the body before being expelled from breathing tubes in the abdomen. Lutz Wasserthal, from University of Erlangen-Nuremberg, Germany, decided to record the pressure in air sacs in the insects’ thoraxes (the chest region) – in addition to recording their in-flight oxygen use and muscle activity – to begin to piece together how the large airborne insects suck air in so powerfully.
The recordings showed immense pressure pulses rising and falling in air sacs in the flight-powering thorax as the insects beat their wings, as well as the oxygen levels in the median dorsal air sacs surging to almost atmospheric levels as they sucked in fresh air. However, as the insects continued flying, the oxygen levels in the air sacs near the insect's waist began to decline, as used air that had fuelled the strong flight muscles returned to the air sacs before being expelled.
And when Wasserthal teamed up with Peter Cloetens at the European Synchrotron Radiation Facility, France, to take a close look inside the powerful moths with intense X-rays as they flew, the duo could see the forceful flight muscles expanding the gigantic air sacs in the thorax. The air sacs were behaving like a colossal suction pump, sucking air in through breathing tubes at the front of the insect before expelling it like a piston out of tubules in the insect's rear.
So, hawkmoth flight muscles have a dual use, simultaneously powering flight while also sucking in the air they require through suction-pump air sacs in the thorax to fuel their powerful flight muscles during each forceful wingbeat, keeping the moths aloft as they flutter from dawn to dusk.
