Hornets are large social wasps (Vespa). They do not consume wood for nutrition or energy. Instead, hornets are predatory insects that harvest cellulose fibers from wood and plant matter solely as a building material. This collected material is used to construct the protective structure that houses their colony.
Why Hornets Harvest Wood
Wood harvesting is necessary for constructing the vespiary, the communal nest required for the colony’s survival. Hornets use the cellulose fibers to create a protective outer envelope and the internal comb structure where the queen lays eggs. In the spring, a fertilized queen emerges from hibernation and builds a small initial nest for her first batch of offspring.
Once the first generation of sterile female workers matures, they expand the nest throughout the summer season. These workers are the primary collectors, scraping wood to acquire the raw materials. The resulting nest provides a secure, climate-controlled environment that shelters the developing larvae and the colony from predators and harsh weather.
The Transformation: From Wood Fiber to Paper Nest
The transformation of wood into a flexible, paper-like material is a mechanical and chemical process performed by foraging worker hornets. A hornet uses its mandibles to scrape thin shavings of weathered wood from surfaces, creating a fine wood pulp rich in cellulose fibers.
The insect mixes this wood pulp with salivary secretions containing proteins and natural adhesives. This mixture forms a moist paste carried back to the construction site. As the hornet spreads the paste in thin layers, the saliva evaporates, causing the material to dry and harden into durable, lightweight paper. The resulting paper often displays distinct color bands reflecting the different sources of wood collected.
Assessing the Damage to Wooden Structures
Hornets typically target weathered, unpainted, or soft surfaces because they are easier to scrape. Common targets include old wooden fences, deck railings, unfinished lumber on sheds, and dead tree branches. This activity leaves characteristic visual cues, appearing as scraped, vertical channels or furrowed grooves on the wood surface.
The damage caused by hornets is cosmetic and minor compared to the deep tunneling damage caused by wood-boring insects like termites or carpenter bees. Hornets only scrape the superficial surface fibers and do not bore into the structure itself. In most cases, the activity does not compromise the structural integrity of a sound home or building.
Extended harvesting on the same wooden object, such as a weathered fence post, can cause noticeable deterioration over time, requiring surface repair or repainting. Property damage concerns are more often related to the nest’s location, particularly when built inside a wall cavity or attic. In these cases, the nest’s size or the moisture it holds can degrade surrounding building materials and insulation, necessitating professional removal and repair.