A laboratoryexperiment was conducted to evaluate the level of effects by differentconcentrations of indigenous entomopathogenic fungus, Metarhizium anisopliae(Metsch.) Sorokin spores by dipping the non-target organisms, the silkworm,Bombyx mori L. in the fungus suspension at laboratory condition inRampur, Chiwan, Nepal. The selected most virulent fungus isolate, among 26 wastested at different concentrations of 107, 106, 105, 104, 103 and 102 number of spores per ml includinga control each replicated thrice to each of 30 fourth instar silkworm larvae.The mortality of silkworm larvae due to fungus started only after five days ofthe treatment and finally caused 70, 44.44, 28.88, 26.66, 23.33 and 3.33percent death of silkworm larvae with 107, 106, 105, 104, 103 and 102 spores per ml of fungal conidialconcentrations respectively. The larval body weight was significantly lowereven one day after treatment in the lots treated with 107 spores as comparedto other concentrations. On the third and fourth day of treatment, there was nosignificant difference in the body weight of silkworm larvae in all thetreatments. There was significantly lower weight in the lots treated with 107 spores afterfifth, sixth and seven days of treatment but after eighth days, there was nosignificant difference in the body weight with the treatments. The laboratoryresult indicated that even a small number of conidia of M. anisopliae (Metsch.)Sorokin caused mortality and was found hazardous to silkworms.