Abstract: Expert system is a recently emerging techology that promises to reduce expense associated with human expertise for some restricted problem domains. The paper describes a pine caterpillar control expert system and talks about its establishment and its structure. Then it discusses its advantages and disadvantages. It also tells how to use the expert system and gave some examples to explain the case. Finaly it outlines TOES expert system tool with which the system is generated.

Key words: Expert system, Dendrolimus puntatus, Pest management