This study measured the respiratory patterns in the tenebrionid beetle, Onymacris multistriata, using flow-through respirometry to measure carbon dioxide emission from the mesothoracic spiracles separately and simultaneously with that from around the elytral case. 96% of the total CO2 emitted was via the mesothoracic spiracles. These spiracles used a discontinuous gas exchange cycle similar to that measured from other tenebrionid beetles. Although the circadian rhythm of the beetles resulted in changes to the period durations and cycle frequencies in the discontinuous gas exchange cycles, the mesothoracic spiracle remained the major site for gas exchange. Thus the subelytral cavity plays a different role in respiration other than the elimination of CO2 build-up. It is expected that other arid dwelling flightless beetles will also be shown to use the mesothoracic spiracle as the major route for CO2 emission.