Entomopathogenic nematode (EPNs) Steinernema carpocapsae was tested against the Locusta migratoria L., 5^th instar nymphs under laboratory conditions. The mortality of nymphs maintained on three concentrations (10, 20 and 40 IJs/g) nematode-inoculated sand was particularly high. Nematode was effective, causing 100% mortality of fifth nymphal instars after third days of treatment. The impact of S. carpocapsae parasitation on L. migratoria immune defense was closely examined, after both 24-48h post treatment with LC₅₀ of nematode the activities of phenoloxidase (PO), peroxidase (POD), α and β estrases (ESTs) and glutathione-S-transferase (GSTs) enzymes of the whole body were estimated. S. carpocapsae affect locust causing high mortality rate, which significantly increased in concentrations and time dependent manner, this effect might be because of enzyme system distraction. These results demonstrated that, the entomopathogenic nematode broke host immunity, by the changes of enzymes activities; that provide an overview about the efficiency of nematode and its effects on L. migratoria.