Blood Circulation in Insect Wings
It has long been known that blood circulates in the wings of insects. Apparently the phenomenon was reported first by Baker (1744) who observed it in the wings of a grasshopper. Since then it has been reported for numerous species in several orders and there is now little doubt that it occurs to some degree in all winged insects. It is true for definitive wings as well as for developing ones, and for modified wings such as tegmina, elytra, hemelytra, and halceres as well as for those that are specialized for flight.