Survey was carried out at Elgemmeza  Agricultural Research Station in  a Colton field  for  Piacing sucking pests and associated predators along two successive seasons (2013 & 2014) during May-August months by using examination of leaves and plants shaking methods, during vegetative and flowering stages. The toxic eilect o fthrec pesticides on piercing sucking pests (whitetly and jassids) and its side effect on true spiders were also studied. Moreover, the toxic effect of three pesticides on cotton leafworm,  Spodoptera littoralis and its side effect on true spiders. Results showed that, the highest numbers of spiders in cotton fields were recorded in  August, in  addition, the highest families  occurrence were Linyphiidae and Philodromidae representing 39.02 and 21.8 %, respectively. As for the average numbers of collected predators, there were significant differences in  the total  numbers of true spiders & aphid lion  and other predators  (Ladybirds,  Rove beetle,  Flower bugs). As for pesticides, Applud gave the highest average numbers of reduction percentages of white fly  stages infested cotton plants followed  by Acetamprid and KZ oils. The decrease percentages of true spiders as side effects of applied pesticides were 29.35 and 21.05 % for Lufenuron and Difluhenzuron and 43.77 % for Profenofos in  cotton fields.  It could be concluded that true spiders played an important role in  suppressing pest populations and in delaying pest outbreaks in the cotton growing season.