A cDNA library of Macrocentrus cingulum embryos, excised from their host Ostrinia furnacalis six days after parasitism was constructed. After synthesizing the first-strand cDNA using limited amount of mRNA isolated from total RNA, the doublestrand cDNA was amplified with long-distance PCR method. Then the ligation of the Sfi I digested cDNA to the Sfi I digested vector [lambda]TripIEx2 was performed and the phage was packed to construct the full length cDNA library. It was determined that the titer of unamplified library was 0. 75 x 106 pfu [center dot] mL-1 and the percentage of recombinant clones was 96.77%, and the titer of amplified library was 0. 5 x 1010 pfu [center dot] mL-1 by plating E. coli XL1-Blue. Biochemistry; Genetics Macrocentrus cingulum (Braconidae); Nucleic acids; Molecular genetics, cDNA library none