Oak trees ,Quercus spp are considered as an important vegetation which naturally growth in Iraq, Kurdistan region, elevations reached 600-1900 m. over sea level. Its characters, slow growth, and non resistant for highly temperature. The low yields of Oak forests are returned to numerous factors, their infestation with insects pests. Field study results of the major insect pests of Oak trees in koya region that showed there are different percentage of infestation according to the kind of insect, species of tree, and the part of plant that has been infested.
It was noted that the Oak gall wasps, Andricus spp are high and the most important insects on the natural Oak trees , Quercus infectoria Oliv. (gall Oak), Q. aegilops L. (normal Oak) and Q. libani Oliv. ( Liban Oak) with a mean of infestation reached ( 88 , 85 and 45 ) % respectively, While there was a least infestation with Oak fruit weevil , Curculia spp a mean reached 23 and 20 insect on the trees of gall Oak and normal Oak of locations Kosar and Bawaji in Koysinjaq region.
The results of field study showed a highest percentage of Euproctis melania S . on the different parts of plants for , Quercus infectoria Oliv. and Q. aegilops L. , with a mean of 66 and 45 insect , respectively , While there was a lowest infestation with Oak moth , Lymantria dispar L. with mean reached 3 and 24 insect for the same of both species of Oak . In addition to the presence of Oak steam borer, Cermbyx dux F., Oak fruit moth , Cydia fagiglandana Z. and Oak aphid , Tuberculoides sp. on the different Oak trees .The results showed a number of predators that attack insects was found on Oak trees and the highest density of predators where the ladybird, Coccinella septenpunctata L. with a mean 27.8, spiders, Eutetranychus sexmaculatu (22.4 %) and predator bugs, Orius sp.(1.8 % ).