A large, gray or dark-colored paper nest hanging from a tree branch or under your eaves almost certainly belongs to the bald-faced hornet, the insect most people mean when they search for a “black hornet.” These football-shaped nests can grow up to 24 inches tall and 18 inches wide by late summer, housing 100 to 400 workers. Despite the name, bald-faced hornets aren’t true hornets at all. They’re a type of aerial yellowjacket in the genus Dolichovespula, and they build the most recognizable paper nests in North America.
What the Nest Looks Like
Bald-faced hornet nests are enclosed structures made entirely of paper, produced when the queen and her workers chew weathered wood fibers and mix them with saliva. The resulting paste dries into a layered, papery shell that ranges from light gray to dark gray, sometimes with streaks of brown or tan depending on the wood sources nearby. The outer envelope has a distinctive scalloped texture, which helps distinguish it from the smoother, more uniform nests built by other aerial yellowjackets.
Inside, the nest contains three or four horizontal tiers of comb cells, similar in layout to honeycomb but made of paper rather than wax. Each tier hangs from the one above it. A single opening at the bottom of the nest serves as the entrance and exit for every hornet in the colony. Early in the season, when only the queen is building, the nest starts out roughly the size of a golf ball. By late summer it can rival a basketball or larger.
Where You’ll Find Them
Bald-faced hornets strongly prefer trees and shrubs for nesting, typically at least 3 feet off the ground and sometimes as high as 60 feet. A nest tucked deep in a tree canopy may go unnoticed all summer until the leaves drop in fall. They also build under eaves, overhangs, and other sheltered spots on buildings, though nests attached directly to structures are more commonly made by their close relative, the aerial yellowjacket.
You won’t find these nests underground or inside wall voids. If you’ve spotted a dark nest in a bush along a walkway, in a low tree branch near your porch, or hanging from your roofline, location alone is a strong clue that bald-faced hornets are the builders.
The Colony’s Seasonal Timeline
The entire colony starts with a single queen who survived the previous winter by hibernating in a protected spot, often under bark, in a log pile, or inside a wall cavity. She emerges in spring, finds a suitable site, and begins constructing the first small cells on her own. She lays eggs, feeds the first batch of larvae, and raises a handful of workers who then take over nest construction and foraging duties.
From that point, the nest expands rapidly through the summer. Workers add new comb tiers, enlarge the paper envelope, and defend the growing colony. The population peaks at 100 to 400 workers by late summer or early fall. In the final weeks of the season, the colony produces new queens and males. These mate, the new queens disperse to find overwintering sites, and every other member of the colony, including the old queen, dies as temperatures drop. The papery nest is never reused the following year.
How Aggressive They Are
Bald-faced hornets are among the most defensive stinging insects you’ll encounter. They will aggressively pursue anyone who gets too close to the nest, and unlike honeybees, each hornet can sting multiple times. Most stings happen when people accidentally stumble onto a nest they didn’t know was there, especially nests hidden in low shrubs along paths or near doorways.
These hornets also have an unusual defense mechanism: they can squirt venom from their stinger directly into the eyes of a perceived intruder, causing immediate tearing and temporary blindness. This behavior is rare among stinging insects and makes close encounters with an active nest particularly risky.
A typical sting produces immediate sharp pain, followed by swelling, burning, and itching at the site. In some people the swelling spreads to a larger area over the next day or two. For anyone with a venom allergy, multiple stings or even a single sting can trigger anaphylaxis, a whole-body allergic reaction that causes difficulty breathing, a drop in blood pressure, and can be life-threatening without prompt treatment with epinephrine.
What to Do If You Find a Nest
If the nest is high in a tree, well away from foot traffic and outdoor living areas, you can often leave it alone. The colony will die off naturally with the first hard frosts, and bald-faced hornets are effective predators of flies, caterpillars, and other pest insects. A nest that’s out of the way is doing useful work in your yard.
Nests near doorways, porches, play areas, or paths are a different story. The defensive radius around an active nest is large enough that regular foot traffic will provoke attacks. Removing a mature nest with hundreds of workers is genuinely dangerous, and attempting it yourself with a can of spray is one of the most common ways people end up with dozens of stings at once. Professional pest control operators handle active nests using protective equipment and targeted treatments, typically at dusk or dawn when the full colony is inside the nest and hornets are least active.
Preventing Nests Before They Start
The best window for prevention is early spring, before or just after queens emerge from hibernation in March and April. A queen investigating your home is looking for two things: a sheltered cavity to build in and a nearby source of weathered wood to scrape for building material.
Sealing structural gaps is the single most effective step. Any opening roughly half an inch or larger is big enough for a queen to enter. Common entry points include gaps between fascia boards and soffits, deteriorated airbrick covers, openings around cables and pipes, and damaged soffit panels. Exterior-grade caulk works for small gaps in masonry. Stainless steel mesh with openings smaller than about 10 millimeters covers vents and soffit ends that still need airflow.
Maintaining exterior wood also helps. Queens preferentially scrape fibers from weathered, flaking wood surfaces. Painted or sealed timber is less attractive as a raw material source. If you’ve had a nest on your property before, check that same area in early April. Finding a golf-ball-sized starter nest with only the queen present is far simpler and safer to deal with than discovering a full colony in July.
Is It a Bald-Faced Hornet or Something Else?
Several insects build paper nests, so identification matters. Paper wasps build small, open-faced combs with no outer envelope, usually under eaves or porch ceilings. You can see the individual cells directly. European hornets, the only true hornet in North America, sometimes build enclosed nests in tree hollows or wall voids, but their nests are typically brown rather than gray and are less commonly exposed on tree branches.
The bald-faced hornet itself is distinctive: a large, stocky insect (about three-quarters of an inch long for workers) that is mostly black with white markings on the face and the tip of the abdomen. If the insects entering and leaving your gray, football-shaped nest match that description, you’re looking at a bald-faced hornet colony.