The biological characteristics ofEuplectrus laphygmaeFerrière, which was a gregarious ectoparasitoid of the larvaeSpodoptera litura (Fabricius), were studied in this paper. The results showed that the largest numbers of eggs laid by one femaleE. laphygmae was 139, and the average numbers was 73.69 in the laboratory.E. laphygmae female laid 1-5 eggs on one individualS. litura larvae (sometimes 6-9 eggs), the eggs were laid on the back of the 1-4 abdominal segments mostly, with fewer on the lateral side and none on the venter.E. laphygmae mostly...