The life history and development of the coccinellid Pseudoscymnus tsugae sp. nov. Sasaji & McClure from Japan is described. Both larva and adult feed on all stages of the hemlock woolly adelgid, Adelges tsugae Annand, a serious pest of eastern and Carolina hemlock in eastern United States. There are 4 larval instars, a prepupa, and pupa. Total development time from hatch to adult emergence required 29.8 d at 20°C and 17.9 d at 25°C. Incubation time was 10.3 d at 20°C and 6.7 d at 25°C. At 14-21.5°C, males matured at 30 d and females at 31.8 d with a preoviposition period of 35 d. At 25°C, males matured at 18.8 d, whereas the female preoviposition period was shortened to 22.4 d. In the laboratory, mean longevity was 162.9 d and 125.6 d for females and males, respectively, with individuals of both sexes that lived >300 d. The mean lifetime fecundity was 279.9 eggs with a maximum of 513 eggs over a mean oviposition period of 14 wk. The mean sex ratio in the laboratory is 1:1. P. tsugae displays facultative diapause and is capable of producing successive generations in the laboratory when its prey is available, indicating its excellent potential for mass rearing as a biological control agent of A. tsugae.
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