Evolutionary explanations are lacking as to how so many exquisite and critical features could have been assembled to make the functioning defence mechanism. Recent research has found that, in some species of the beetle, the spray is emitted, not as a continuous stream but as a pulsed jet. Analysis of the internal structure of the beetle suggests that the valve action to produce the pulsed effect is virtually automatic. Pulsed delivery systems have several advantages over non-pulsed systems. High discharge velocities are not dependent on musculature control.
Muscles merely introduce materials to the reaction chamber and have no direct role in expulsion.
Control of the duration and direction of the spray is facilitated. Propulsion is not by muscles, so the reaction can be maintained as long as the reagents are available. The beetle is free to put its energies into directing the spray and adjusting it to match the threat. There are possible benefits from reducing the danger of thermal denaturation of the enzymes. Cool reagents are moved into the reaction chamber, permitting a lower average temperature and promoting stability of the enzymes.