The spider, Nigma conducens (Cambridge, 1876) was locality recorded in El-Gharbia Governoraye, Egypt. It was collected from cotton plants cultivated in El-Gemmeiza Agricultural Research Station, El- Gharbia Governorate. The biology of the spider, Nigma conducens (Cambridge,1876) was studied under laboratory conditions of 28 °C and 60-65 % RH on nymphs and adult stages of the cotton jassid, Empoasca lybica (De Berg.).Males pass through five spiderling instars, while females pass through six spiderling instars before reaching adult stage. The mean of female preoviposition, oviposition and post-oviposition periods were 15.8, 19.5 and 44.5 days, respectively. The female laid 3-6 egg sacs. The mean number of egg/sac was 12-19 eggs. The incubation period of eggs was 11.7 days. The life cycle of this spider was 59.2 days for male and 62.6 for female. Adult longevity, life span, fecundity of female and food consumption were also studied.