This study was investigated the seasonal occurrence of Metcalfe pruinosa (Say) in Chungbuk province and established the optimal control timing. Population densities of nymph and adults were investigated and egg hatching period and oviposition period was examined from three locations (Cheongwon, Jincheon, Eumseong area). Egg hatching period was investigated. The first day of egg hatching observed on May 25, the day of peak egg hatching was on May 29, and the perfect accumulative egg hatching ratio was on Jun. 13. Oviposition period of M. pruinosa female was observed the cut branch (cut within 10 cm length, 1 cm dia.) of oak tree, an althea, and an acacia under stereoscope. The first oviposition was observed at Jul. 28 and continually increased until late-Sept. with sharply increased at mid-Aug. Population density of M. pruinosa nymph was observed the cut branch (cut within 30 cm length, 1 cm dia.) of oak tree, an althea, an acacia, and pear tree. Population density began decreased showing after highest density with 25.3 (Jul. 1). The adult was first appeared at Jul. 11 and showed highest population density with 13.1 (Aug. 4) and then continuously decreased. To control M. pruinosa at pear orchard, optimal control timing for nymph was judged from Jun. 13 to Jul. 2, because of its small size of body and exuviae, low damaging by honeydew producing, low wax materials produced. Second control timing was judged at early Aug., when the adult invading to the pear orchard from near forest and the period before oviposition. The control agents for M. pruinosa were not yet registered, but will be anticipated to register the chemicals such as penitrothion WP, acetamiprid WP, dinotefuran WP, lambda cyhalothrin, thiamethoxam SP in 2012.