The heart is a pump attached to a long tube that extends from the abdomen to the head. The blood is pumped through this tube and released into tissues. The blood seeps through the tissue back to the abdomen. In this process blood is sucked back into the heart and pumped forward again. Butterflies have no transportation of oxygen in the blood.
Butterflies have valves called spiracles along either side of their bodies.
Most of these spiracles are located along the abdomen and they allow oxygen to enter. Some of the other spiracles exhale carbon dioxide. Oxygen will travel directly to where it is needed and pass into the tissue.