Insect's metabolic rate and patterns of gas-exchange varies according to different factors such as: species, activity, mass, and temperature among others. One particular striking pattern of gas-exchange in insects is discontinuous gas-exchange cycles, for which many different hypotheses regarding their evolution have been stated. This article does not pretend to be an extensive review on the subject, rather to focus on the work performed on the haematophagous bug Rhodnius prolixus, a model organism used from the mid XX century until present days, with the great influence of Wigglesworth and his students/collaborator's work. I have no doubt that the renovated field of insect gas-exchange has a bright future and will advance at large gaits thank to the help of this model organism, R. prolixus, whose entire genome has recently being unraveled.