They can glide, hover, perform startling aerobatics, and can even fly backwards. Yet for all this, their flight mechanisms especially those involved with hovering and manoeuvring at high speed, is incompletely understood. Dragonflies have large wings. This allows them to be economical in terms of energy expended per meter of distance traveled. It has been estimated that for an average-sized American emperor dragonfly, a power rating of 0.039 Watts is available for flight.
Flight is fueled by carbohydrates or by fats.
Migrating Dragonflies store large deposits of fats which seems to be the 'fuel of choice' for long flights. A highly modified tracheal system is required to deliver oxygen to the wing muscles at a rate fast enough to sustain flight at high speeds. Air is driven in and out of the tracheae through open spiracles, keeping the muscles supplied with oxygen, through the action of the thoracic plates. Dragonflies need lots of heat. On cold overcast days, it is unlikely to see them in flight.