New record of two folivores in Erythrophleum fordii plantations in Vietnam Author Truong, Pham Xuan 0009-0000-9530-2893 Special-Use and Protection Forests of Hanoi, Hanoi 12200, Vietnam; https: // orcid. org / 0009 - 0000 - 9530 - 2893; https: // orcid. org / 0009 - 0007 - 1909 - 8780 phamxuantruongvfu@gmail.com Author Thai, Nguyen Hoang 0009-0003-5210-1815 Hoai Duc A High School, Hanoi 13223, Vietnam; https: // orcid. org / 0009 - 0003 - 5210 - 1815 Author An, Nguyen Le Ha 0009-0005-3209-3277 SenTia School, Hanoi 12011, Vietnam; https: // orcid. org / 0009 - 0005 - 3209 - 3277 Author Thao, Tran Thi Phuong 0009-0003-5986-1374 Vietnam National University of Forestry, Hanoi 13417, Vietnam; https: // orcid. org / 0009 - 0003 - 5986 - 1374 * Corresponding author. Email: phamxuantruongvfu @ gmail. com Author Ha, Dinh Thi 0009-0000-9530-2893 Special-Use and Protection Forests of Hanoi, Hanoi 12200, Vietnam; https: // orcid. org / 0009 - 0000 - 9530 - 2893; https: // orcid. org / 0009 - 0007 - 1909 - 8780 text Ecologica Montenegrina 2025 2025-03-27 83 60 67 https://doi.org/10.37828/em.2025.83.6 journal article 10.37828/em.2025.83.6 2336-9744 16960700 Assessment of Biston and Clanis damage in Erythrophleum fordii trees Field observations were carried out on Biston and Clanis during 2024 in 2 to 16-year-old E. fordii plantations in Hanoi , Hoa Binh and Bac Giang provinces, Vietnam . Life-cycle laboratory studies were used to compliment the field studies, and this was undertaken in the SPFH, Hanoi , Vietnam . The E. fordii plantations examined being damaged by Biston and Clanis were 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 Biston and Clanis larvae 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 ni is the number of infected trees at damage index i , vi is the damage index at level i , N is total number of trees assessed, and V is 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