Whether wasps like wood is a common question, and the answer is a nuanced yes: certain species interact with wood not for sustenance, but as a building material. Wasps do not consume wood for food like termites, which break down cellulose into nutrients. Instead, they selectively harvest wood fibers to construct the intricate, lightweight nests necessary for their colony’s survival. This behavior is a specific process of material collection, and understanding this mechanism helps differentiate superficial surface damage from true structural threats.
The Biological Purpose: Why Wasps Turn Wood into Paper
The attraction to wood is a purely architectural one, driven by the need for cellulose to create the paper-like pulp of their nests. Social wasps, particularly Paper Wasps (Polistes species) and Hornets, use their mandibles to scrape wood fibers from various sources. These collected fibers are then masticated and mixed with the wasp’s saliva, which acts as a binding agent and creates a pliable paste.
This paste is carried back to the nest site and applied in thin layers, which dry quickly into a strong, papery substance. The resulting nest material is essentially a form of primitive paper, which the insects use to build the hexagonal cells for their young and the protective outer envelope of the nest. The characteristic color variations seen in a finished nest often reflect the different wood sources the colony foraged from.
Wasps prefer weathered, untreated wood, which is softer and easier to break down into pulp. The sun’s ultraviolet light and moisture degrade the wood surface, making the cellulose fibers accessible. This is why areas like unpainted deck railings, wooden sheds, and old fences frequently become targets for material collection during the spring and summer building season.
Identifying Wasp Activity and Distinguishing Damage
Homeowners often worry that wasp activity signals significant structural damage, but the scraping behavior of paper wasps is typically superficial and does not compromise the strength of the lumber. Visual inspection of the wood surface reveals the telltale signs of wasp activity: faint, linear, or elongated scrape marks where the fibers have been removed. These marks are shallow, follow the grain of the wood, and look like the surface has been lightly sanded away.
It is important to distinguish this superficial scraping from the structural damage caused by wood-boring insects, such as Carpenter Bees. A female carpenter bee chews a perfectly round entrance hole into the wood to excavate tunnels for her eggs. Unlike the wasp’s scraping, this creates deep galleries and can lead to structural weakening over time, often accompanied by small piles of sawdust, known as frass, beneath the entry point.
Wasps collect their material from a source and then build their nest in a separate, protected location. Paper wasp nests are usually umbrella-shaped and suspended from a single stalk under sheltered areas like eaves, porch ceilings, or window frames. Recognizing the nature of the damage—scraping versus boring—is the quickest way to determine the level of threat to the wood structure.
Preventing Wasps from Using Structural Wood
The most effective method for discouraging wasps from harvesting wood fibers is to eliminate the accessible source material they seek. Applying a proper coat of paint, stain, or clear sealant to exposed wood hardens the surface, making it difficult for the wasps’ mandibles to scrape off the fibers. This simple application effectively denies them the required raw material.
Addressing moisture issues and repairing any signs of decay also helps, as wasps naturally gravitate toward wood that is already softened by weathering or dampness. For areas that cannot be painted, such as untreated wooden furniture, applying certain oils can create a protective barrier. Tung oil or teak oil, for example, cures to a hard finish that eliminates the loose, soft fibers wasps prefer, while their strong odor may also act as a repellent.
Using certain scents can also deter foraging wasps. Natural deterrents like essential oils, specifically peppermint, clove, or citronella, can be diluted and sprayed onto susceptible wooden surfaces to make the area less appealing for material collection. Consistent application, especially during the early spring when queens begin to build their nests, can proactively safeguard structural wood from being turned into paper.