Abstract: The pollinating insects of the invasive weed Mikania micrantha H.B.K. and their foraging behavior were studied in an open population in South China. A total of 30 species of insects belonging to 19 families of 6 orders were recognized. The most common floral visitors were arranged in Hymenoptera, Diptera and Hemiptera such as Apis sp., Calliphoridae and Syrphidae. Calliphoridae was the most frequent flower visitor. The peak of visiting frequency of Apis sp. was 9:00-10:00 and 15:00-16:00, while those of Calliphoridae and Syrphidae were both 11:00-12:00 and 14:00-15:00. Environmental factors and the plants having the same floral period (such as Polygunum chinense L.) had a certain influence on the visiting frequency of M. micrantha.