Abstract: Lobesia incystata Liu et Yang is described as new to science．It is allied to Lobesia reliquana (Hubner)，but differs from L．Reliquana by the following characters: with two close thin transverse strigulae across the middle of the basal patch of forewing；the soeius of male gnitalia with a group of minute bristles；the cucullus broad and shott，not more than 1/3 of the whole valva in length；the Spc₂ of saceulus close to Spcl and separated into two lines along the bottom margin of the sacculus．Holotype:♂，Allotype:♀，Paratypes:20♂♂，20♀♀，Anning，Yunnan， 1900m，25．IX．1984，collected by Yang Guang．Holotype，Allotype，Paratypes 10♂♂，10♀♀are deposited in Institute of zoology。Academia Sinica and the others are deposited in the Biological Department of Yunnan University．Host:Keteleeria evelyniana Mast．Distribution:Kunming，Anning，Tonghai，Huaning，Yuxi，Lufeng，in Yunnan Province．This new species is a monophagous insect，feeding on the buds of the native economic tree of Yunnan Province．Keteleeria evelyniana and causing severe damage to the nursery stocks and young trees of the host．It has three or four generations a year in Kunming．The threshold for development and the effective thermal summation of a generation are 9.9℃and 612.2 day-degree．As mentioned in this paper，the details of the morphology，bionomics，six parasitic insects and control measures of pest are given．