Abstract The domesticated silkworm (Bombyx mori) is both economically significant and a valuable model organism. However, challenges persist in silk production, particularly in preserving silkworm cocoons. The wild silkworm (Bombyx mandarina), a close relative, with long-term pupal characteristics, could address storage and industrial silk production issues. We conducted interspecies hybridization between domestic and wild silkworms, successfully introducing the long-pupal period trait into the domestic silkworm through genomic integration. Here, we presented the telomere-to-telomere genome assemblies of three silkworm strains (KA, L, and M) with long-term pupal characteristics. The genome assembly sizes ranged from 453.82 Mb to 461.92 Mb, with high contig N50 values and completeness. We predicted over 14,000 protein-coding genes and identified strain-specific fragments. This research enriches the domestic silkworm pan-genome project and provides a foundation for further genetic studies. By introducing the trait, we have for the first time reported a phenomenon of genomic introgression between domestic and wild silkworm, and have also opened up a new avenue for silkworm breeding.