In this study, we elevate the innate immune response of Bombyx mori against Staphylococcus aureus infection. The fifth instar Bombyx mori larvae was used and infected by intrahaemocoelic injection of bacterial sample. The haemolymph was collected from the infected and control group larvae at 24 hours of post infection and stored at -4°C in eppendorf tubes to use. Phenoloxidase a key component of the insect innate immune system. The activity of phenoloxidase was increased in the haemolymph of infected larvae at 24 hours of post infection. The total protein concentration in the haemolymph was determined according to the Lowry method and total haemocyte population in the haemolymph was estimated by trypan blue test. Protein content and total haemocyte population increased in infected larvae when compared to control larvae at 24 h post infection with bacteria. The haemolymph was placed directly over a sterilized glass slide and slides were prepared by Giemsa staining method. Giemsa stain confirmed that aggregation of haemocytes in the haemolymph of infected Bombyx mori larvae
