Identifying damage characteristics and analyzing damage degrees of ancient buildings affected by pests and diseases are crucial for developing maintenance strategies and preventive conservation measures for them. It is challenging to find insect adults or larvae on wooden components in surveys, hindering the identification and analysis of biological hazards. In this study, we focused on the examination of damaged wooden components within Longxing Temple, a nationally protected ancient building in Zhijin County, Guizhou Province, and analyzed and identified the causes of damage to the wooden components of this ancient building following several steps: identifying tree species, observing and analyzing surface and internal hazard characteristics, assessing degradation of three major components in wood, and identifying insect specimens. The results show that the wooden components were made from local Liquidambar species native to Guizhou, as determined by tree species identification. The pests caused elliptical wormholes on the wood surface ranging from 6 to 20 mm in length and from 3 to 6 mm in width. The internal cavities were filled with a mixture of powdered and granular wood chips and feces, extending flat along the wood texture. Furthermore, based on the analysis of damage characteristics, it was concluded that the wooden components were damaged by Eurypoda antennata. The analysis of wood composition in the feces show that E. antennata primarily degraded cellulose, with minimal degradation of hemicellulose and virtually no degradation of lignin. After surface and non-destructive internal testing analysis, it was determined that E. antennata caused a severe (Level 4) damage to the building’s wooden components. This study could provide valuable reference for identifying characteristics of biological damage in ancient buildings, and a scientific basis for the preventive conservation of ancient buildings.