【Objective】To make clear Eunotus aequalivena life history,living habits,parasitic situation as well as the relationship between its host Eulecanium gigantea happening on trees Ulmus pumila and Sophora japonica in Mongolian Autonomous Prefecture of Bayingolin,Xinjiang,China. 【Method】The methods of field point survey,random survey,indoor observation and breeding were used. 【Result】7 parasite wasp species of E. gigantea were collected,in which E. aequalivena accounts for 21. 16% as a dominant species in the to...