[Insecticidal activity of pyrethroids for houseflies and German cockroaches].

Insecticidal and knock-down effects of eight pyrethroids, belonging to 2 types as to their chemical structure and specific action towards the nervous system, on the domestic flies' and German cockroaches' imago were assessed comparatively. Pyrethroids of the 2nd type, especially deltametrine, proved to be more effective against domestic flies as well as German cockroaches. Activity of the pyrethroids of the 1st type featured rapid knock-down effect and was practically independent from varying concentrations. The knock-down was reversible even at high concentrations. In case of the 2nd type of pyrethroids, the knock-down effect was concentration-dependent. Domestic flies, on the whole, were more sensitive to the effect of pyrethroids of the 1st type. The use of pyrethroids of the 2nd type against nonflying sinathropic insects would be advisable because they produce a higher insecticidal effect as well as irreversible knock-down.