A rounded, dark-colored lump attached to a tree trunk or branch is almost certainly a termite nest, specifically an arboreal (tree-dwelling) nest built from a material called carton. These nests are common in warm, humid climates and range from the size of a football to over a meter across depending on the species and colony age. Whether the nest is a problem depends on the termite species, the health of the tree, and how close it is to your home.
What the Nest Is Made Of
Arboreal termite nests look solid and rough-textured, usually dark brown or grayish-black. They’re constructed from “carton,” a mixture of chewed wood fibers, soil particles, saliva, and fecal material that the termites cement together. When dry, carton hardens into a surprisingly tough shell that insulates the colony from temperature swings and predators. Inside, the nest is honeycombed with tunnels and chambers where the queen lays eggs and workers tend larvae.
You’ll often see mud tubes (sometimes called shelter tubes) running from the nest down the trunk toward the ground. These enclosed pathways let termites travel between the nest, their food sources, and the soil without being exposed to light or dry air. If the tubes look fresh and moist, the colony is active. Dry, crumbling tubes suggest the nest may be abandoned.
Which Termites Build Tree Nests
Several termite genera build arboreal nests, but the most common belong to the Nasutitermes group. In eastern Australia, for example, Nasutitermes walkeri is a well-known tree-nesting species found in coastal bushland. It builds rounded nests on trunks and is mainly associated with stressed trees, dead wood, poles, and timber on the ground. Importantly, it rarely attacks buildings.
In the southeastern United States and Hawaii, Formosan subterranean termites are the primary concern. They usually nest underground, but when enough moisture is available they build aerial carton nests in wall cavities and inside trees. Unlike many termite species that stick to dead wood, Formosan termites actively target living trees, hollowing them out from the inside.
In tropical regions of Central and South America, Africa, and Southeast Asia, dozens of Nasutitermes and related species construct elaborate arboreal nests that can persist for decades. The species varies by geography, but the nest structure and carton material are remarkably similar worldwide.
Does the Nest Harm the Tree?
This is the question most people really want answered, and the short version is: it depends on the species and the tree’s condition. Most arboreal termites feed on dead wood, fallen branches, and decaying organic matter rather than living tissue. A healthy tree with a termite nest on its exterior may not be suffering any damage at all. The termites are using the trunk as a mounting point, not necessarily as a food source.
The exception is species like the Formosan termite that do consume living wood. When these termites infest a tree, they can hollow out the interior heartwood until the trunk loses structural integrity. A tree that looks fine on the outside can be almost entirely hollow inside. Warning signs include the trunk sounding hollow when tapped, branches dying back without obvious cause, and the tree leaning or swaying more than its neighbors in wind.
Trees that are already stressed, damaged by storms, or weakened by disease are more vulnerable. Nasutitermes walkeri, for instance, is mainly associated with stressed trees rather than healthy ones. So a nest on a struggling tree can be both a symptom and an accelerating factor of decline.
Should You Remove It?
If the nest is on a tree well away from your house and the tree appears healthy, removal is often unnecessary. Many arboreal termite species play a valuable ecological role, breaking down dead wood and recycling nutrients back into the soil. The nest itself is a food source for birds, lizards, and other wildlife.
Removal makes more sense in a few situations. If the tree is within about 15 to 20 meters of a structure, the colony could eventually find its way to your home, particularly if the species is one that attacks buildings. If the tree is visibly declining or hollowed out, it becomes a falling hazard during storms. And if you’re in an area with Formosan termites, any active colony near a home warrants professional attention because of their aggressive feeding habits and large colony sizes (mature Formosan colonies can contain millions of individuals).
Simply knocking the nest off the tree rarely solves the problem. The queen and much of the colony may be inside the trunk or underground, and they’ll rebuild. A pest control professional can identify the species, assess whether the colony poses a risk to nearby structures, and treat the tree or surrounding soil if needed.
How to Tell Termites From Other Nests
Tree nests can also be built by ants, wasps, or bees, so a quick visual check helps narrow things down. Termite carton nests are hard and brittle with a rough, earthy texture. Ant nests (particularly those of tree ants) tend to be made of woven leaves or have a papery, lighter appearance. Wasp and bee nests are distinctly papery or waxy and often have visible entry holes.
If you break open a small piece of the nest surface (wear gloves), termite workers are pale, soft-bodied insects roughly the size of a grain of rice. Nasutitermes soldiers have a distinctive pointed head (called a nasus) they use to squirt a sticky defensive secretion. Ants, by contrast, are darker, harder-bodied, and have a clearly pinched waist between their thorax and abdomen. Seeing mud tubes running along the bark is another strong indicator of termites rather than ants or other insects.