Laboratory studied were carried out in an attempt to disclose the effect of antifeedant (Neem) at different concentrations on one day old of the 5^th nymphal instar of the desert locust, Schistocerca gregaria (Forskal) by feeding technique. Results showed that Neem caused 42% mortality after 12 days from treatment of LC₅₀ values. Neem decreased the THC after 2 and 4 days while significant decreased after 6 days compared to control. The free amino acids were non significant between Neem and control after 2 days while significant decreased after 4 and 6 days from treatment. The trehalase was non significant between Neem and control after 2 days while increased after 4 and 6 days from treatment.