Deconstructed Forests of the Past: What Types of Wood and Fungi did Beetle Larvae Feed upon Based on Amber Inclusions?

The composition of today’s forests is shaped by multiple factors: climate zones with specific temperature and precipitation patterns, altitude, soil composition, natural disturbances, and anthropogenic influence all affect forest structure and biodiversity. In warm, humid climates, wood decomposition is rapid, driven by fungi and microorganisms; however, this process slows in drier and cooler conditions. Insect larvae also play key roles in this breakdown, fragmenting plant material and promoting forest floor humification through their frass.

This ecological function has remained the same over millions of years. Fossilized resins—ambers—offer unique insights into ancient forest ecosystems. Amber often preserves insect larvae, especially beetle larvae that lived in or near resin-producing trees. Beetle larvae feeding on hardwood, softwood, fungus-infested wood, and directly on spores and hyphae appear widespread in amber deposits from diverse regions. They must have helped recycle nutrients and supported decomposition in past forests.

To infer these ancient ecological relationships, I analyze larval morphology. Mouthparts are especially informative: chisel-like mandibles point to hardwood borers, while brushes or setose structures indicate fungal feeders. Body shape also provides insights—flattened forms suggest life under bark or on exposed surfaces under strong environmental pressures, while cylindrical shapes imply life within soft or decaying substrates. This presentation showcases a diverse array of insect larvae from ambers of various origins and ages, using morphological and shape analyses to reconstruct their ecological roles and feeding strategies, supported by a range of methodologies. The new findings deepen understanding of ancient forest ecosystems.