Susceptibility status of wild Ph. argentipes of Patna, Bhojpur and Samastipur districts (Bihar) were tested against 4 per cent DDT, following the standard WHO technique with WHO test kits. Ph. argentipes from Samastipur district had become tolerance to DDT, LT50 being 1.28 h. Ph. argentipes from Patna and Bhojpur districts were however found susceptible to DDT.