Field experiments were conducted at two successive growing seasons (2003 and 2004) at Sakha Agricultural Station, to evaluate the initial and residual effect of Marshal and Sulphur against cotton aphid, Aphfs gossypit (Glov) Jassid, Empoasca lypica {de Berg.) and whitefly, Bemisfa tabacf (Geno) and their associated natural enemies. beside the effect of weather factors (mean temperature and relative humidity). Summarized results indicated that, Marshal induced the highest initial and residual reduction giving 100 and 97.3 % in the first season and 88.8 and 78.7 % reduction respectively, in the second season against aphid, while in the two seasons Sulpher gave high initial reduction, where it exhibited 88.2 and 69.2 98 respectively. and induced a moderate residual effect, where it exhibited 50.0 and 21.? % reduction respectively. Also, Marshal and Sulphur against Jassid induced high initial effect, where they cauded 72.1 98 and 76.7 % reduction respectively, and a moderate residual effects giving 50.? and 48.2 98 reduction reSpectively, during 2004 season, but their effect during 2003 season were less than 2004 season. Also, the effect of both pesticides on whitefly (mature and immature stages) were moderate to weak effect. As for their side effect on the associated natural predators, Marshal induced moderate effect while Sulphur exhibited a slight effect against (true spider, Chrysopa spp., Peederus alfierif, Orius spp. and Scymnus spp.) Regarding the effect of temperature and relative humidity on the population density of pests, temperature effected on the population of aphid, whitefly (mature and immature stages) and their predators negatively and insignificant while had negative and significant on Jassld during the two seasons. On the other hand, relative humidity effected positively significant on aphid and whitefly, and positively and insignificant on Jassid during 2003 season, meanwhile it exhibited negativly insignificant effect on all insects and their predators during 2004 season.