Abstract: Du-ensiform gall caused by Du-ensiform gall aphid, Kaburagia rhusicola on a sumac tree, Rhus potaninii, is one of the important Chinese gallnuts in China. The population of the aphids in the gall grows rapidly, increasing as much as 3 000 times in about 3 months. But it drops sharply out of the gall owing to the high mortality and low vitality. The aphids from the same gall can complete their life history in a year or two years or even more. Although the survival rate of those individuals which finish their life history in a year is about 0.3%~1.5% of the total nymphs inoculated on the second hosts, mosses, in the last year, the population can increase as much as 40~180 times. The individuals which complete life history in two years as a result of extremely high mortality on the second hosts grows poorly. So people have to make good use of the individuals finishing their life history in a year and manage to reduce mortality of the aphid during overwintering on the second hosts to obtain a high yield of the gall.