Female and maleAmblyseius longispinosus(Evans) andA. womersleyi(Schicha) were reared in an incubator at 28°C and a photoperiod of 13:11 (L:D) h. They were supplied with eggs ofTetranychus kanzawaiKishida for food.A. longispinosusmatured in 5.02 and 5.0 d, and consumed 13.84 and 11.2 spider mites eggs, respectively.A. womersleyimatured in 4.92 and 4.67 d, and consumed 15.32 and 11.54 spider mite eggs, respectively. In the first 10 d after ec1osion, adult femaleA. longispinosusandA. womersleyiconsumed an average of 26.43 and 32.07 spider mite eggs daily, and laid 2.92 and 3.07 eggs per day, respectively.A. womersleyideveloped slightly faster thanA. longispinosusand was more voracious. Larvae of both species were observed eating spider mite eggs. Adult femaleA. womersleyiincompletely consumed spider mite eggs when food was abundant. When mated with maleA. longispinosus, all femaleA. womersleyioviposited but with reduced fecundity. Only male offspring were produced and 47.8% of eggs were nonviable. However, only 1.5% of femaleA. longispinosusthat mated with maleA. womersleyioviposited, but offspring of both sexes were produced. Hybrid F1progeny inherited the maternal setal length of dorsal seta L8 in all reciprocal matings. These findings suggested that these two mites are distinct species. Their life cycles, food consumption, reproductive compatibility, and geographical distribution are discussed.