New record of two folivores in Erythrophleum fordii plantations in Vietnam Truong, Pham Xuan Thai, Nguyen Hoang An, Nguyen Le Ha Thao, Tran Thi Phuong Ha, Dinh Thi Ecologica Montenegrina 2025 2025-03-27 83 60 67 923TH Leach 1815 [372,450,914,940] Insecta Geometridae Biston Animalia Lepidoptera 1 61 Arthropoda genus  Field observations were carried out on  Bistonand  Clanisduring 2024 in2 to 16-year-old  E. fordiiplantations in Hanoi, Hoa Binhand Bac Giangprovinces, Vietnam. Life-cycle laboratory studies were used to compliment the field studies, and this was undertaken in the SPFH, Hanoi, Vietnam. The  E. fordiiplantations examined being damaged by  Bistonand  Claniswere 10 – 20 hectares in size, typically with 1,660 trees per hectare. In each province, 10 plots/age (each 500 m 2) were randomly selected and leaf damage from  Bistonand  Clanislarvae was recorded on 60 trees in each plot. The damage was classified at five levels as follows: 0 = no leaf damage; 1 = leaf area loss <25%; 2 = leaf area loss 25 to <50%; 3 = leaf area loss 50 to <75%; and 4 = leaf area loss ≥ 75%.  Data analysis Following the results of damage classification, the damage incidence (P%) was calculated using Equation 1 ( Chi et al.2021):  P% = (n/N) × 100(1) where: n is the number of trees attacked by leaf-feeders; N is total number of trees assessed. The damage severity (R%) in each plot was calculated using Equation 2 (VAFS 2023):  R% = (( Ʃni× vi)/(N × V)) × 100(2) where  niis the number of infected trees at damage index i,  viis the damage index at level i, Nis total number of trees assessed, and Vis the maximum damage index used for classification. The damage severity level was ranked based on the average damage index as follows: very severe damage (R%> 75%); severe damage (75% ≥ R%> 50%); medium damage (50% ≥ R%> 25%); slight damage (25% ≥ R%> 0%) and no damage (R% = 0%).  Results