The "Manta"(Juvenile hormone analogue-Methoprene) was topically applied at 36.48 and 72 hrs after the fourth ecdysis to eri silkworm, Samia cynthia ricini with doses of 2.75$mu extrm{g}$/$mell$, 4/0$mu extrm{g}$/$mell$ and 8.0$mu extrm{g}$/$mell$. The eri silkworm responded to 2.75$mu extrm{g}$/$mell$ of "Manta" applied at 72 hrs after the fourth ecdysis, resulting in improvement of larval, cocoon, pupal and cocoon shell weigths.ocoon shell weigths.