The desert locust Schistocerca gregaria is an economically dangerous pest invading several countries in North Africa and West Asia. The present work aims at assessing the effects of Nigella sativa extracts, compared to Azadirachta indica extract Neemazal, on survival and development of this pest. Treatment of the newly moulted penultimate instar or the newly moulted last instar nymphs with Neemazal leads to the decrease in gained somatic weight. It, also, exhibiteds an inhibitory effect on the development of penultimate instar nymphs and intervenes with the metamorphosis program because that some nymphal-adult intermediates were formed. After treatment of the newly moulted penultimate instar nymphs with N. sativa extracts, the lethal effects of both the methanolic and petroleum ether extracts were exerted early in the same treated nymphs but no mortality rats were detected among the treated last instar nymphs by methanolic extract. Treatments of the same nymphs with N. sativa extracts led to the decrease in the body weight gain.  The methanolic or petroleum ether extract significantly inhibited the nymphal development. Treatment with n-butanolic extract resulted in disrupted metamorphosis because some nymphal-adult intermediates appeared proportionally to the concentration level. Treatments of the newly moulted last instar nymphs with N. sativa extracts deprived the nymphs to obtain normal somatic weight. Methanolic extract caused a slightly suppressed developmental rate. The n-butanolic extract exhibited a reverse action because significantly accelerated developmental rates, were recorded.