Abstract: 【Aim】 Drepanococcus chiton is a newly recorded Coccidae pest in China in recent years. It can pose a great threat to the agricultural production and ecological environment, and its harm to Phyllanthus emblica was first found and described in western 
Yunnan. It is of great significance to study its spatial distribution, and morphological and biological characteristics for its monitoring and control. 【Methods】 From May to September 2019, we investigated the occurrence and population densityof D. chiton on three test plantations of P. emblica in Baoshan, Yunnan Province by sample-plot survey and analyzed its spatial distribution pattern by clump intensity index. From January to December 2020, we bred D. chiton indoors and in the experimental field, respectively, by fresh branches of P. emblica without the pest and P. emblica plants grafted with D. chiton female adults, and observed the reproductive mode, postembryonic development, morphological characteristics, developmental duration and life history. 【Results】 In western Yunnan, D. chiton was distributed in groves of P. emblica aggregately, its damage rate was 32%-56% and its population density was 10.95-94.26 individuals per plant. It has two generations a year. The fertilized female adults overwinter on the host branches and their oviposition periods are during January-February, June-July and October-November. The growing periods of the 1st-2nd instar nymphs are during January-March and June-September, and the peak periods of eclosion of male adults and copulation of adults were in mid-late March and during late July-middle August, respectively. The reproductive mode is bisexual reproduction and the postembryonic development is oviparous type. The oval and orange yellow eggs are accumulated outside the matrix and protected in wax shell, and their average developmental duration is 8-13 d. The 1st instar nymphs are flat, smooth, orange yellow, active and diffused with the wind and molted in 12-18 d. The 2nd instar nymphs are slightly arched on the back, secrete dentate waxy bulges and differentiate into female and male in 7-10 d. The 3rd instar female nymphs have large arched backs, transparent thin wax shells and yellow green or brown bodies, and their average duration is 13-18 d. The longest average duration of female adults is 50-62 d, their abdomens press back before laying eggs, the number of eggs laid per female is 847.03±13.72, and the egg hatching rate was 97.68%. The male 
has three developmental stages: prepupa, pupa and adult. The prepupal duration is 5-7 d and the pupal duration 7-10 d. The male adults have developed front wings, degenerated rear wings and developed external genital process, and their shortest life span is only 1-3 d, so they are difficultly seen in the forest. 【Conclusion】 D. chiton is distributed in groves of P. emblica in western Yunnan aggregately and the female adults have proper reproductivity. The dispersal stage of the 1st instar nymphs is from January to March and the developmental stage of piercing-sucking mouthparts of the 2nd instar nymphs is from June to September when they are asthenic. Therefore, it is suggested to carry out comprehensive control at these periods of a year.

Key words: Drepanococcus chiton, morphological characteristics, life history, biological characteristics; Phyllanthus emblica