Yellow-legged hornet nests are egg-shaped structures made of paper-like material, typically found high in trees by late summer. A mature nest can grow larger than a basketball and house 3,000 to 5,000 workers. Because Vespa velutina is an invasive species in the United States and a serious threat to honey bees, knowing how to identify these nests is important for reporting and removal efforts.
Three Stages of Nest Development
Yellow-legged hornet colonies don’t build one nest and stay put. They go through three distinct nesting stages over the course of a season, each producing a different-looking structure.
Embryo nests appear in early spring when a single queen emerges from winter dormancy. These are roughly the size of a tennis ball, smooth on the outside, and typically found in sheltered spots like porches, eaves, or garden sheds. The queen builds this starter nest alone, lays her first eggs, and raises the initial batch of workers herself.
Primary nests come next, constructed by those first workers. They range from softball to watermelon size and have a shell-like appearance. About 77% of primary nests are found in or on man-made structures, so garages, barns, and the undersides of decks are common spots. These nests are temporary. They serve as a staging area while the colony grows enough to relocate.
Secondary nests are the final, permanent colonies. The transition from primary to secondary nest happens by the end of July. These nests are significantly larger, often exceeding basketball size, and are usually visible from late summer through fall. Despite their imposing shell-like exterior, they’re made of the same chewed-wood paper material as the earlier stages. A secondary nest at peak season holds one queen and anywhere from 3,000 to 5,000 workers.
Where Secondary Nests Are Built
Once the colony outgrows its primary nest, workers build the secondary nest high in the tree canopy. About 74% of secondary nests end up in trees, with oaks and pines being the most common hosts, followed by plane trees, alder, cedar, and tulip trees. Another 22% are found on man-made structures, and a small percentage (around 5%) turn up in other natural locations.
The height makes these nests surprisingly hard to spot. Researchers tracking yellow-legged hornets in invaded regions often follow individual hornets back to the colony, watching for the moment a hornet flies upward into the canopy. Without that kind of directed search, a nest tucked among dense foliage 40 or 50 feet up can go unnoticed until leaves drop in autumn and reveal its outline.
How to Tell Them Apart From Other Nests
The nest most commonly confused with a yellow-legged hornet nest is that of the bald-faced hornet, a black-and-white wasp native to North America. Both species build exposed, paper nests that hang from tree branches or structures. The key differences come down to the insects themselves: bald-faced hornets are smaller, not true hornets, and don’t attack honey bee colonies the way yellow-legged hornets do. If you can get a clear look at the hornets entering and leaving, yellow-legged hornets have a mostly dark body with distinctive yellow legs and an orange face.
European hornets, which are established across much of the eastern U.S., nest differently. They prefer protected cavities like tree hollows, wall voids, or underground spaces. If you find a large, exposed, egg-shaped paper nest hanging from a tree limb rather than hidden inside a cavity, that rules out European hornets and points toward either a yellow-legged hornet or bald-faced hornet colony.
Late-Season Changes Inside the Nest
For most of the summer, a yellow-legged hornet nest is a worker factory. The queen lays eggs, workers forage and expand the nest, and the colony’s population climbs steadily. Late in the season, the colony shifts its priorities. Workers begin raising new queens (called gynes) and male drones instead of more workers. These reproductive hornets will leave the nest, mate, and the newly mated queens will find sheltered spots to hibernate through winter. The original nest is never reused the following year.
This late-season shift matters because it’s the point at which the colony’s invasive potential multiplies. A single large nest can produce dozens of new queens, each capable of founding her own colony the next spring. That makes finding and eliminating nests before this reproductive phase especially valuable for containment.
What to Do If You Find a Nest
If you spot a nest you suspect belongs to yellow-legged hornets, leave it undisturbed. State agriculture departments and university extension programs have set up reporting systems specifically for this species. Clemson University, for example, runs a dedicated reporting site where South Carolina residents can submit a photo of the suspected hornet or nest. Georgia’s Department of Agriculture maintains a similar system. The consistent instruction across agencies is the same: photograph the nest, note its location, report it, and let trained field inspectors handle removal. Disturbing the nest yourself risks both personal injury and the chance that hornets scatter before professionals can eliminate the colony.
Because this species was first detected in the U.S. in 2023 (in Savannah, Georgia), agencies are still in the early stages of tracking its spread. Every confirmed nest report contributes to the broader eradication effort. Even a report that turns out to be a bald-faced hornet nest helps narrow the search.