The life history and seasonal population growth of the southern red mite,Oligonychus ilicis(McGregor), infestingIlex crenata‘Convexa’ are reported. Mean developmental times (in days) at 24°C are: egg incubation, 6.5; active larva, 1.4; quiescent larva, 1.0; active protonymph, 0.9; quiescent protonymph, 0.9; active deutonymph, 0.9; and quiescent deutonymph, 1.1. Females deposit 2.4 eggs/day, totaling 36 eggs/lifetime. Adults live for 16.5 days at 24°C.Field population growth ofO. iliciswas compared in random counts of mites infesting carbaryl-treated and untreated Japanese hollies during the 1977 season. Treated groups showed a 6-fold increase in the number of immature mites and a 13-fold increase in the number of adult females and eggs compared to populations on untreated hosts. Populations peaked in November at 387 females/100 carbaryl-treated leaves and 25 females/100 untreated leaves. Treated populations produced 50.9 diapausing eggs/leaf and resulted in severe injury to host fOliage as compared to only 3.8 overwintering eggs/leaf and no leaf damage on untreated hollies. Neither the treated nor untreated populations followed the seasonal population growth pattern previously described. Data suggest these differences are attributable to the adverse effects of carbaryl on indigenous predatory populations.