Termites eat cellulose, the tough structural sugar found in plant cell walls. Wood is their most famous food source, but they’ll consume anything cellulose-rich: dead leaves, grass, paper, cardboard, cotton fabric, and even the paper backing on drywall. What makes termites remarkable isn’t what they eat but how they digest it, relying on an entire community of microorganisms living inside their gut to break down a material most animals can’t touch.
Cellulose Is the Common Thread
Every item on a termite’s menu shares one ingredient: cellulose. This complex sugar makes up roughly half the dry weight of wood and is one of the most abundant organic compounds on Earth. Termites consume it in many forms, including live and dead wood at various stages of decay, dry leaves, grasses, fungi, lichens, and humus in soil. In a home, that translates to structural lumber, firewood, books, cardboard boxes, cotton clothing, and the paper layer covering drywall (they leave the gypsum core alone).
Termites can also chew through materials that contain no cellulose at all, like foam insulation and thin plastic, but they aren’t eating those. They tunnel through them to reach wood or soil on the other side. The distinction matters: a foam barrier won’t starve termites, because they’re just carving a path, not looking for a meal.
How Termites Digest Wood
Cellulose is notoriously hard to break down. Cows need a four-chambered stomach to do it. Termites solve the problem with a dense community of bacteria, archaea, and single-celled protozoans packed into their hindgut. No single microbe handles the job alone. The protozoans swallow tiny wood particles, and bacteria living inside those protozoans produce enzymes that split cellulose into short-chain fatty acids, primarily acetic acid (the same compound in vinegar). The termite’s cells absorb those fatty acids and use them for energy, much the way human cells use glucose.
Digestion starts in the mouth, where saliva helps grind wood into progressively smaller particles. Those particles travel to the gut, where the microbial community ferments and hydrolyzes cellulose into simple sugars and fatty acids. The gut microbes do more than just digest cellulose. They maintain an oxygen-free environment that allows fermentation, break down lignin (the rigid compound that gives wood its hardness), and even fix nitrogen from the atmosphere, compensating for the fact that wood is an extremely nitrogen-poor food.
This relationship is obligate, meaning neither the termites nor their gut microbes survive without each other. When a young termite hatches, it must acquire these microorganisms from nestmates before it can digest wood at all.
How Termites Get Enough Nitrogen
Wood is almost all carbon and very little nitrogen, which creates a nutritional challenge. Protein, DNA, and many essential molecules require nitrogen to build. Termites have evolved several strategies to cope. Their gut bacteria fix atmospheric nitrogen the way soil bacteria do for plants, converting it into a usable form. Termites also recycle nitrogen aggressively: they consume the bodies and shed exoskeletons of dead nestmates, and they store nitrogen waste as uric acid in specialized fat body cells rather than excreting it. Workers eventually pass stored uric acid to the king and queen, who possess the enzyme needed to break it down and channel the nitrogen into egg production.
What Different Species Prefer
Not all termites eat the same way. Their dietary habits depend heavily on moisture needs and habitat.
Subterranean termites are the most common structural pests. They nest in or near soil, which provides the moisture they need to survive, and build mud shelter tubes to reach wood above ground. They prefer wood that’s already slightly decayed because it’s softer and easier to digest. When feeding, they follow the grain, eating the softer springwood and leaving behind the harder summerwood. Fallen trees, stumps, dead wood touching the ground, and structural lumber in homes are all fair game.
Drywood termites need very little moisture and never contact the soil. Their colonies live entirely inside the wood they eat, including structural lumber, dead tree limbs, utility poles, fences, decks, and furniture. They can thrive even in desert conditions. Drywood termites cut across the wood grain rather than following it, leaving behind a distinctive pattern of chambers connected by tunnels, many of which they pack with small fecal pellets.
Dampwood termites require high moisture levels and typically infest decayed wood that stays wet, either from soil contact or a water leak. They’re most common in cool, humid coastal areas and in forest environments where they colonize stumps and fallen logs. They carve large, open galleries inside the wood where they both live and feed.
Fungus-Farming Termites
One group of termites, found mainly in Africa and parts of Asia, takes a completely different approach. Instead of relying solely on gut microbes, these termites cultivate a specific fungus called Termitomyces inside their nests. Workers forage for dead plant material and run it through their gut once to extract simple sugars. They then deposit the partially digested waste into structures called fungus combs, where Termitomyces grows in the warm, humid, competitor-free conditions the nest provides.
The fungus breaks down the remaining cellulose and lignin far more thoroughly than the termites could alone. Workers then eat the fungus, especially its protein-rich nodules packed with asexual spores, gaining access to nutrients and enzymes the fungus produces. Over time, colonies select for the most productive fungal strain: clones that grow faster and decompose more material are preferentially used to seed new combs, so each colony ends up maintaining a single, highly efficient cultivar. The result is a system that decomposes plant biomass almost completely.
Woods That Termites Avoid
Termites don’t eat all wood equally. The heartwood of certain tree species contains natural chemical compounds that repel or poison them. In a USDA study that fed Formosan subterranean termites a single wood species for six weeks, six out of ten woods tested showed meaningful natural resistance: teak, Alaskan yellow cedar, redwood, Brazilian jatoba, Peruvian walnut, and Honduran mahogany all caused termite mortality rates above 75 percent.
Teak stood out as the most toxic. Termites forced to eat only teak actually died faster than a starvation control group, meaning something in the wood actively kills them rather than simply being hard to digest. On the other end of the spectrum, southern yellow pine and spruce were the most palatable, with high termite survival rates. Birch and red oak fell somewhere in the middle. Even Peruvian walnut, which killed most termites, still sustained enough feeding damage to be comparable to birch and red oak, showing that “resistant” doesn’t always mean “untouched.”
Natural resistance is useful for choosing outdoor lumber or furniture wood, but it’s not a guarantee of protection. Hungry colonies with limited alternatives will test nearly any wood, and resistance diminishes as heartwood weathers and ages.