Abstract
Gnathotrichus materiarius is listed as an alien ambrosia beetle in European fauna. This is an invasive species from North America, which was found in Europe (France) in the 1930s. In Poland, it was recorded in 2015. Already in 2017 numerous infestations of G. materiarius on lying Pinus sylvestris wood were obsereved. G. materairius is a xylomycophagous species and wood damage to its feeding is similar to that caused by striped ambrosia beetle Trypodendron lineatum. The paper presents sites of G. materairius occurrence found in 2016 and 2017. These include 15 sites located in managed forests (5 forest districts) as well as in 2 national parks situated along south-western border of Poland. G. materairius beetles were found in pheromone-baited traps used to monitor Ips duplicatus and I. amitinus or collected from infested Scots pine wood. The paper presents the description and characteristics of wood damage due to G. materiarius as well as its distinguishing features.