Abstract: To evaluate the joint-control potential of Ophraella communa and Epiblema strenuana to the alien invasive weed Ambrosia artemisiifolia, a field test was conducted in the summer of 2008 in Langli, Changsha county, Hunan province. 15 cm height clean A.artemisiifolia seedling was transplanted on April 15, 2008 in a filed of 2000 m², where a field release of the two insects was conducted in amount of 0.27 million adults×hm^-2 (1.8 per plant on average) for O. communa and 0.35 million moths×hm^-2 (2.3 moths per plant on average) for E.strenuana, respectively. A counterpart field of 1200 m² was the control without releasing. The population dynamics of the two insect species and control effect on A.artemisiifolia were investigated every 6 days from July 9 to August 27, 2008. The results showed that the population of the two insect species increased rapidly. At 21^st and 42^nd days after released, the population of O.communa larvae reached the peak, with the values of 69.02 and 61.38 beetles×plant^-1, respectively. The peak populations of O.communa eggs, pupae and adults were observed at 35^th, 28^th, and 35^th day after released, which were 877.5 eggs×plant^-1, 34.6 pupae×plant^-1 and 12.8 adults×plant^-1, respectively. The gall density of E.strenuana reached a maximum, with value of 39.6 larvae×plant^-1 at 14^th day after released. The joint-control effect of the two insects on A.artemisiifolia was significant, and the plant height of A.artemisiifolia in the releasing field was significantly shorter than in the control field after 49 days. The leaf-control indices of O.communa on A.artemisiifolia increased with time, and all leaves of the whole A.artemisiifolia plants were eaten up after 56 days, and 100% of A.artemisiifolia plants died in the released field. A.artemisiifolia plants lost the breed fertilities, and seed yields were 0. This implies that artificial migration of the two insect species can suppress on A.artemisiifolia population nicely in summer.