Abstract: A genomic library of silkworm Bombyx rnori (Chinese species Dongfei×Huahe) was constructed. 12-20 kb DNA fragments from partially digested silkworm genomic DNA withsau3A were recovered and inserted into the BamHI site of the bacteriophage vector Λembl4. The recombinant molecules were packaged in vitro and amplified to a permanent library. The number of the bacteriophage recombinants was 5.5X10⁵ pfu. This number exceeded the theoretical number necessary to cover the whole genome. Futher examination showed: 1. The phenotype of bacteriophages in the library was Spi^-; 2. Different recombinants contained dif-ferent foreign DNA fragments; 3. After screening the library by hybridization, some recom binants containing the foreign DNA homologous to the probe of mosquito esterase BI gene had been isolated. These results demonstrated the reliability of the library.

Key words: Bombyx mori——genomic library——vector λEMBL4