Five pyrethroids are used in much the same manner
as pyrethrum extract (Fig. 2). They are highly
insecticidal but not persistent enough for agricultural
use. Three are primarily knockdown agents and the
other two are very potent for kill. Household sprays
are usually a mixture to mimic the action of pyrethrum.
They contain a knockdown agent, a more
insecticidal component, and a synergist, normally
piperonyl butoxide. With the exception of kadethrin,
these compounds are chrysanthemates.