Abstract: This paper compared the realized sex ratio of several lac insect pecies,based on the previous and the authors' researches.The results showed that the realized sex ratio of Kerria ruralis with the same life cycle and on the same host trees differed with years,while that of K.ruralis and K.lacca with the same life cycle and in the same year was different with different host tree species.On the same host trees,the realized sex ratio of K.ruralis andK.sindica was different with different life cycles,even in the same year.The realized sex ratio of K.ruralis differed on the same host trees,when the brood lac was different.The temperature and humidity of environment,and the structure,nutrient contents and growth speed of host trees had effects on the realized sex ratio of lac insect.The mechanism of the difference in realized sex ratio of lac insect might be due to the local mate competition and the local resource competition.

Key words: Life rubbish, Turfgrass, Carpet turf, Ecological engineering of environment, Medium selection and compounding