Insects have played an important role in an understanding of the fossil records of plants, revealing insights into their past ecological interactions (Labandeira et al., 2001; Hulcr et al., 2015). This case study presents the results of the examination of a unique conifer xylite specimen from the Baltic amber-bearing deposits, showing evidence of insect behaviour and its connection to resin production. The specimen contains a system of cylindrical borings, likely created by xylophagous beetles, characterised by longitudinal tunnels connected by cross tunnels and chambers. These structures, filled with a fossilised resin that preserves fungal hyphae and singular coprolites, indicate a complex interaction between plants, insects, and fungi (Franceschi et al., 2005; Nagy et al., 2022).

Specimen analysis included imaging using stereoscopic microscopy, UV light photography, and Fourier Transform Infrared (FT-IR) spectroscopy to confirm the resin as succinite, the most abundant fossil resin of Baltic amber deposits (Kosmowska-Ceranowicz, 2015). The results suggest that the borings represent insect habitation and feeding traces, which triggered a plant defense mechanism involving extensive resin production. This finding suggests that wood-boring insects could have had a significant impact on resin secretion and amber formation (Cognato & Grimaldi, 2009).

This study provides new insights into the ichnotaxonomy of trace fossils in xylic substrates and the paleoecology of amber-producing forests. The research further highlights lignite deposits as valuable data sources on fossil resin preservation and taphonomy.