Numerous insects live in forests as a component of forest ecosystem. Forest insect pests are defined certain insects when they adversely affect ecological, economic, and social values that we associate with forest. Kinds of forest insect pests are continually changed as a result of change of forest ecosystem and the introduction of foreign alien insect pests. Forest pest management is the maintenance of destructive insects at tolerable levels by the planned use of a variety of preventive, suppressive, or regulatory tactics and strategies that are ecologically and economically efficient and socially acceptable. However, the system of forest pest management is slighly different according to the nation and case of insect pests. Currently, the most important insect pests of Korea are Monochamus beetles and Platypus koroensis, which are insect vectors of pine wilt disease and oak wilt disease, respectively. Major forest insect pests are Thecodiplosis japonensis, a gall maker of pine needle and sapsucking insects such as black pine bast scale, Matsucoccus thunbergianae, Corythucha ciliata, Lycorma delicatula. Defoliating insects, such as Dendrolimus spectabilis, Hyphantria cunea, Agelastica coerulea, Acantholyda parki, and phloem boring insects, such as Tomicus piniperda and Ips bark beetles are also regarded as major forest insect pests. Management of forest insect pests are different from kinds of insect species. Control methods currently used are as follows; (a) Chemical control : ground and aerial spray of low-toxicity insecticide, trunk injection of systemic insecticide, fumigation, etc. (b) Biological control : release of parasitic wasps, use of Beauveria bassiana. etc. (c) Physical or mechamical control : burn, crush, etc. (d) Silvicultural practice : salvage cutting, clear cutting and reforestation, breeding of resistant trees, etc.