The damage status of L. invasa on different Eucalyptus varieties( clones) were surveyed in the field,and effects of Eucalyptus varieties on fitness,development and reproduction of this pest were studied in the study. Results showed that:( 1) Most of the major Eucalyptus varieties( clones) could be attacked by L. invasa in Fujian Province,and galls formed on E. urophylla × E. camaldulensis DH201-2,E. gradis QG3,E. dunnii,E. urophylla cU6,E. grandis × E. urophylla GL9,E. robusta and E. exserta; L. invasa could develop and complete its life cycle on above varieties.( 2) The damage degree of different Eucalyptus varieties( clones) was different from fitness degree to L. invasa. L. invasa had different selection frequency,fecundity and number of larvae per gall on different Eucalyptus varieties( clones).( 3) In addition to little difference in female ratios,L. invasa feeding different Eucalyptus varieties( clones) had extremely significant differences in the indicators such as number of emerged L. invasa,body mass of female adult,fecundity,longevity,etc.( 4) According to the fitness index( FI),the host plants of L. invasa were divided into 4 types by cluster analysis: suitable host,moderately suitable host,less suitable host and unsuitable host; the fecundity of each female was more than 70 eggs in suitable host,which was adequate to lead to potential population outbreak of the pest. Host fitness index could be used as a comprehensive evaluation index for screening of resistant varieties( clones) in production. The damage status of L. invasa on different Eucalyptus varieties (clones) were surveyed in the field, and effects of Eucalyptus varieties on fitness, development and reproduction of this pest were studied in the study. Results showed that :( 1) Most of the Major Eucalyptus varieties (clones) could be attacked by L. invasa in Fujian Province, and galls formed on E. urophylla × E. camaldulensis DH201-2, E. gradis QG3, E. dunnii, E. urophylla cU6, E. grandis × E. urophylla GL9, E. robusta and E. exserta; L. invasa could develop and complete its life cycle on above varieties. (2) The damage degree of different Eucalyptus varieties (clones) was different from fitness degree to L. invasa. L. invasa had different selection frequency, fecundity and number of larvae per gall on different Eucalyptus varieties (clones). (3) In addition to little difference in female ratios, L. invasa feeding different Eucalyptus varieties (clones) had extremely significant differences in the indicators such as number of e merged L. invasa, body mass of female adult, fecundity, longevity, etc. (4) According to the fitness index (FI), the host plants of L. invasa were divided into 4 types by cluster analysis: suitable host, moderately suitable host, less suitable host and unsuitable host; the fecundity of each female was more than 70 eggs in suitable host, which was adequate to lead to potential population outbreak of the pest. Host fitness index could be used as a comprehensive evaluation index for screening of resistant varieties (clones) in production.