Abstract: The outbreak pattern of Masson Pine Caterpillar(MPC),Demdraolimus punctatus,have both periodic and stochastic characteristics.In different environment conditions the outbreak pattern are different.In frequently outbreak area,the pattern is usually eruptive,while in occasionally outbreak and non-outbreak area the pattern are gradient,emigration,or stable at low population density.The outbreak causes in one hand is high fecundity of MPC and more importantly the existence of large-scale pure pine forests.Outbreaks usually initiate by high temperature and drought or chaotic dynamics under the influence of environmental noise.During the increase phase the dynamics are droved by positive density dependent factors while in decline and endemic phase the negative density dependent factors such as induced host resistance and natural enemies play an important role.Vegetation and invertebrate diversity take a main role in the suppression of MPC outbreaks.

Key words: Dendrolimus punctatus, population dynamics, outbreak mechanism