Lufox interfered with the reproduction and development of Argas persicus when fed adult female and second nymphal instar were topically treated with a single dose (10 ul/tick) of Lufox at three different concentrations (10, 50, and 150 ppm). Generally, the effects of Lufox were dose- dependent, increased by increasing dose concentration, and temporally dependent on the physiological state of the treated tick.         Lufox treatment of the adult female A. persicus at different periods of its reproductive cycle reduced fecundity and fertility of the female tick by decreasing the number and percent hatching of the deposited eggs, respectively. Lufox treatment prolonged the pre-oviposition, oviposition, and the egg incubation periods. The effects were most prominent when females were treated during vitellogenesis (3^rd day after feeding).           Lufox was toxic to A .persicus, induced mortality of the treated newly moulted fed second nymphal instar to reach 100% at 150 ppm. Application of Lufox prolonged the premoulting periods of the treated 2^nd and the resulted 3^rd nymphal instars, delayed, and reduced adult emergence. Also, Lufox treatment led to production of different deformities in legs and inability to shed exuvia of the resulted 3^rd instar nymphs and an inhibition of adult emergence. The probable physiological bases of the observed effects of Lufox on adult female and nymphs were discussed.