The western conifer seed bug, Leptoglossus occidentalis Heidemann (1910) (Heteroptera: Coreidae), is a pest causing significant seed damage on many coniferous species. Although it is originally from Western North America, it occurs in several countries today due to frequent intercontinental exchange of related plant material. Both nymphs and adults feed on seeds by piercing their stylet into cones and thus cause conelet abortion and seed loss. Therefore, the western conifer seed bug is expected to have consequences on natural forest regeneration. But its main damage occurs on pine nut production which is one of the most profitable non-wood forest industry in several Mediterranean countries, including Turkey. The western conifer seed bug was first recorded in Turkey in 2009 and it expanded its range rapidly since then. It occurs in all regions of the country today. We named it as “çam kozalak emici böceği” (pine cone sucker bug). We aimed in this booklet to compile a Turkish review of the international knowledge on L. occidentalis produced so far. We also aimed to produce a summary in English which reviews upto date contribution of the Turkish researchers on the pest. Therefore this summary covers only the parts of the booklet related to Turkey. We also provided English versions of the table and figure legends.