The Sunn pest Eurygaster integriceps (Puton 1881) (Ord. Hemiptera, Fam. Scutelleridae) is the most pests of wheat and barley fields in Nahavand. In recent years, one of the most reasons for the expansion and outbreak Sunn pest is the indiscriminate spraying and with high dose procedures, regardless of the economic injury level, as well as destruction of natural enemies this pest. This project was performed in irrigated wheat fields Khezel vicinity of Nahavand City in a complete randomized block-design, with the aim of reducing the used dose of deltamethrin 2.5%EC in combination with citogitt oil 100%L. Sampling took place in the nymphal stage of 3, 10, 15 days after spraying respectively. The result showed that the effect of different concentrations of recommended insecticide and adding the oil for the characteristics of nymphal instars density and 1000 seed weight of wheat were significant at 1% probability level. Therefore it was found that adding oil accompanied with decreasing insecticide concentration has been effective in reducing Sunn pest population. On the other the application of oil in the incorporation with pesticides can be causing loss of grain water (grain shrink), as well as premature maturation of seeds and loss 1000 seed weight. Therefore its use is not recommended because of the yield loss on the wheat field.
