Abstract: The damage of pine caterpillar (Dendrolimus punctatus Walker) has been controlled after using Dimilin in June, 1993 in pest disaster area of Ningxiang County, Hunan Province. The results of investigation in four types of treatment district including Dimilin, Dimilin + Decis, Decis, and CK show that insect number of species and individuals in shrub layer are higher than those in tree crest after 12 generations. The number of species in control district is more higher than that of other three districts and it is the lowest in Decis district. But the insect diversity of shrub layer and tree crest layer has no conspicuous difference among all treatment districts and the insect diversity of shrub should be enriched furthermore.