Baldfaced Hornet — Fact Sheet

Scientific name: Dolichovespula maculata (Linnaeus, 1763) Common names: Baldfaced hornet, bald-faced hornet, white-faced hornet, bald-faced aerial yellowjacket, bald hornet, spruce wasp, bull wasp, blackjacket, white-tailed hornet Family: Vespidae (subfamily Vespinae) Status in the San Antonio / Boerne corridor: Native, present but not abundant — the only "hornet" people regularly encounter locally

At a glance

Identification

There is essentially no confusing a baldfaced hornet with anything else.

• Color pattern: Bold black-and-white. Not yellow and black. The white face ("bald face") is unmistakable. White markings also appear on the thorax and on the last three segments of the abdomen. Every other common local wasp has yellow markings; baldfaced hornets have white.
• Size: Large — 3/4 inch, noticeably bigger than yellowjackets, roughly the size of a paper wasp but stockier and more robust.
• The nest: The single most reliable ID. If there's a large, gray, football-shaped paper nest hanging from a tree branch, it's a baldfaced hornet nest. No other common wasp in North America builds that kind of nest.

"Bald" in the common name doesn't mean hairless — it comes from the older English word meaning "having a white spot," derived from piebald. The white face marking is the "bald" part. The species was first formally described by Carl Linnaeus in his 1763 Centuria Insectorum.

Not actually a hornet

Baldfaced hornets are not hornets. This matters because it affects how the species is classified, understood, and treated.

True hornets are in the genus Vespa — the European hornet, the Asian giant hornet ("murder hornet"), and the various Asian and European Vespa species. Baldfaced hornets are in Dolichovespula, which is the aerial-yellowjacket genus. Taxonomically, they are much closer to yellowjackets than to any true hornet.

"Baldfaced hornet" persists as the common name because of their large size and aerial nest construction, but the formal entomological classification puts them squarely in the yellowjacket group. Texas A&M AgriLife Extension notes this explicitly: "It actually belongs to the yellowjacket family (Vespidae)" — the only "hornet" reported in Texas, and not a hornet at all.

Biology and behavior

Annual cycle

Like most temperate-zone social wasps, baldfaced hornet colonies are annual. The cycle:

• Spring (April–May in Central Texas): A single mated queen, having overwintered in a protected crevice, emerges and begins constructing a small starter nest. She lays eggs, raises the first brood alone, and builds out the initial paper envelope.
• Summer: First workers emerge (typically after about 19–23 days of larval and pupal development). Workers take over nest expansion, foraging, and brood care. The queen moves to full-time egg laying. Colony grows rapidly.
• Late summer / fall: Colony reaches peak size of 100–700 workers — the largest of any Dolichovespula species. The nest has expanded to its full size of up to 14 inches in diameter and 23 inches in length.
• Fall: The colony enters its reproductive phase, producing males and new queens. These reproductives mate; males die shortly after mating, new queens seek overwintering sites.
• First freeze: Old queen, males, and all workers die. The nest is abandoned.

Baldfaced hornets do not reuse their nests. A 23-inch paper football in your oak tree in February is an empty shell. The colony inside died months earlier, and next year's queens are overwintering somewhere entirely different.

The nest — a genuine engineering feat

The baldfaced hornet nest is one of the more remarkable structures any insect builds in North America:

• Construction material: Weathered wood fibers scraped from old boards, bark, and fences, mixed with saliva and chewed into pulp. The result is essentially hand-made paper.
• Structure: Multiple horizontal combs of hexagonal cells stacked inside a spherical-to-elongated paper envelope. The envelope has a single small entrance at the bottom.
• Size: Can reach 14 inches in diameter and 23 inches in length — a genuine basketball-to-football proportion.
• Color banding: The paper envelope often has visible gray banding from different wood-source collection trips. Looking closely at a mature nest reveals layered construction history.
• Height: Vertical distribution ranges from 1 foot to 65 feet off the ground. Most residential nests are 15–30 feet up in mature tree canopies.

Interior structure: multiple horizontal tiers of comb suspended inside the envelope, with larvae hanging head-down in each cell. The envelope provides weather protection, temperature regulation, and security from most predators.

The "matricide" phenomenon

Here's a documented baldfaced hornet oddity that entomologists still discuss. In studies of mature colonies during the reproductive phase, researchers have found that of 19 nests examined during the reproductive cycle, 14 nests had no queen. Workers in reproductive-phase nests may kill their own queen — or she may die of natural causes just as the colony is transitioning to reproductive output. Matricide has not been directly observed, but the pattern of queenless reproductive nests is consistent enough that queen-killing by workers is considered the most likely explanation.

The reason appears to be evolutionary. Once enough workers exist and queen-destined eggs have been laid, the old queen's presence is actively unhelpful to the colony's reproductive goals. Female workers have the genetic capacity to lay haploid eggs that develop into males — and in the absence of the queen, they can contribute their own reproductive output. Killing the queen at the right moment lets the workers spread their genes.

Dolichovespula also differs from yellowjacket (Vespula) sister species in that some workers produce haploid offspring that develop into males — something Vespula workers generally don't do.

The diet

Adults drink nectar, tree sap, fruit pulp (especially apples and fermenting fruit), and honeydew from aphids. They also scavenge — raw meat, carrion, and insect prey.

Larvae get protein: workers catch live insects (flies caught on the wing, caterpillars, spiders, even other wasps) and chew them into a paste that is regurgitated to the larvae. In return, larvae produce a sugary saliva secretion that the adult workers consume — a feedback loop that helps tie the colony's food economy together.

Baldfaced hornets are effective predators of pest insects — a mature colony removes thousands of caterpillars, flies, and aphids from the surrounding landscape over the course of a summer. North Carolina State University Extension explicitly notes the species is "probably beneficial because they prey on plant pests."

Venom spraying — a real thing

Baldfaced hornets can spray venom from their stingers. This is a documented behavior. When they perceive a threat near the nest at close range, they can aim their stinger and squirt venom a short distance — enough to reach the eyes of an intruder. The venom in the eyes causes intense burning pain and can cause temporary vision loss. This isn't a common behavior — most defense is delivered through conventional stinging — but it's real and it's why professionals always wear eye protection when approaching an active nest.

Local context — San Antonio and the Hill Country

Baldfaced hornets are present but not abundant in the San Antonio to Boerne corridor. They are a forest-edge species, and the less wooded parts of the region (central Bexar County, the drier western reaches) produce fewer calls than the heavily-oaked corridor communities.

Where we see baldfaced hornet nests locally:

• Fair Oaks Ranch mature live oak canopy — classic habitat. Every summer, some fraction of homes with large mature oaks will have a baldfaced hornet nest somewhere in the canopy. Most are 20–30 feet up and functionally out of reach.
• Bulverde and Spring Branch acreage properties — more wooded, more nests. Pecan and live oak stands produce the majority.
• Canyon Lake wooded lots — shoreline oaks and cedar-juniper stands.
• Boerne ISD school campuses with mature trees — recurring service calls.
• Urban San Antonio mature tree neighborhoods — Alamo Heights, Terrell Hills, Monte Vista, Olmos Park, Mahncke Park. Downtown San Antonio's canopy produces a handful of nests every season.
• Less common: on buildings. Baldfaced hornets do occasionally build on building eaves or the sides of structures, but tree sites are preferred when available.

The "when to remove" judgment call

Not every baldfaced hornet nest requires removal. The genuine risk calculation:

• Nest within 10 feet of human activity: Remove. Sting risk is real and defense radius is about 10 feet.
• Nest 15–25 feet up in a canopy tree with no regular human activity below: Usually leave alone. Mark the tree on a map, advise the homeowner to avoid the zone, wait for frost. The colony dies in November and the problem solves itself.
• Nest on a building eave, patio, or outdoor living structure: Remove. Close proximity and predictable human traffic make conflict inevitable.
• Nest in a tree adjacent to a pool, playset, or driveway: Judgment call based on specific geometry. Often remove to be safe.

Every year we have clients who insist on removing a nest that's 40 feet up in an isolated tree corner of a 10-acre lot. We do the work if they want it, but the honest recommendation is "wait for winter." Dead-of-winter removal of an abandoned nest is trivial compared to a live-colony treatment at height.

Risk to humans and pets

Moderate to high within the defensive radius of the nest. Low otherwise.

A baldfaced hornet foraging on flowers or scavenging at a dropped fruit is essentially non-aggressive — she'll ignore you. A baldfaced hornet that perceives you as a threat to the nest is genuinely dangerous. The species defends aggressively, stings repeatedly, and (as noted) can spray venom at eyes.

Sting pain is rated 2.0 on the Schmidt Pain Index — comparable to yellowjackets, less painful than a red wasp. Justin Schmidt described the sting as "rich, hearty, slightly crunchy. Similar to getting your hand mashed in a revolving door." The danger is not individual sting pain but mass envenomation during a nest-defense incident, combined with the venom-spray-at-eyes capability.

Treatment approach

• Daytime reconnaissance, nighttime treatment. Aerial nests are always best treated at dusk or dawn, when workers are inside.
• Extension equipment for canopy nests. Most residential nests are 15–30 feet up. Professional pole-applied aerosols reach this height; homeowner consumer products do not.
• Protective equipment: Bee suit, sealed veil, eye protection (the venom-spray issue is not hypothetical).
• Treatment protocol: Pyrethrin-based aerosol applied to the nest entrance and exterior. Workers return to the nest, contact the treated surface, and die. Treatment continues over 24–48 hours until activity ceases.
• Nest removal: After activity has stopped, the nest is physically cut down and disposed of. Leaving a nest in place doesn't technically matter (they're abandoned annually anyway), but most homeowners want it gone.
• Very high nests (30+ feet): Monitor until frost. Full aerial removal is possible with specialized equipment but expensive; if the nest is high enough to be truly out of human reach, the wait-for-winter approach is legitimate.

Odd, funny, and genuinely true

• Songbirds use baldfaced hornet nest paper. Chickadees, nuthatches, and several warbler species have been documented pulling paper fragments from abandoned nests to use as nesting material for their own broods. An old winter nest is effectively a free construction material depot for the following spring's birds.
• The pheromone chemistry of baldfaced hornet nest defense has been chemically analyzed. Research published in 2016 by Jimenez et al. identified specific pheromone compounds that baldfaced hornets release during nest defense, triggering more workers to join the attack. The chemistry of the alarm pheromone has a kind of "maculatic acid" signature that is specific to D. maculata.
• A male baldfaced hornet sex attractant pheromone was identified in 2018 — "Maculatic Acids" — and published in Angewandte Chemie, a leading chemistry journal. The fact that chemists are isolating and naming pheromones after this species gives you a sense of how well-studied it is.
• Bee moths parasitize baldfaced hornet nests. The female bee moth (Aphomia sociella) — not actually a bee, just similar in appearance — lays her eggs inside active Dolichovespula nests. The moth larvae eat the hornet eggs, larvae, and pupae. Entire hornet colonies can be destroyed from the inside by this parasite.
• Baldfaced hornets have been captured alive in New Zealand — they are not native there, but individual specimens have been collected in Dunedin, suggesting possible accidental introduction events. No established population has ever been documented outside North America.
• A baldfaced hornet nest has three "zones" you can identify at close range. The outer envelope, the inner suspension points where combs hang from the envelope, and the individual comb tiers with cells. You can see all three structures by looking up at an abandoned winter nest with a flashlight — the paper is translucent enough to see interior shadows.
• The "piebald" origin of the name "bald-faced" is a fascinating linguistic fossil. In older English, "bald" simply meant "white-marked" or "having a white spot." A "bald eagle" has a white head; a "baldfaced hornet" has a white face. The meaning drifted toward "hairless" in other contexts but the original sense survives in a handful of specific names.
• The longest recorded baldfaced hornet nest was 58 cm (23 inches) long. That's close to two feet — hanging from a single tree branch, built from paper made by wasps chewing wood fiber all summer. The weight of a nest of that size plus all workers is nontrivial.
• Workers recognize their own nest by cuticular hydrocarbons — surface chemicals on the exoskeleton that function like colony-specific perfume. A baldfaced hornet from one colony can immediately distinguish nestmates from intruders. Research in 1985 by Ryan, Cornell, and Gamboa established this nestmate-recognition system in D. maculata.
• The "bald-faced" marking gets more prominent as the wasp ages. Freshly emerged workers have a less contrasty face pattern than older wasps. This is because the cuticle darkens over the first few days after emergence, making the white areas appear whiter against a darker background. It's why old worker photos show the classic striking face pattern and fresh-emergence photos look slightly washed out.

FAQ hooks (for LuperIQ / SEO)

• Big gray wasp nest in my tree — what is it?
• Are baldfaced hornets real hornets?
• How do you remove a hornet nest from a tree?
• Are baldfaced hornets dangerous?
• What's the difference between a hornet and a yellowjacket?
• Will baldfaced hornets come back to the same nest?
• Do baldfaced hornets sting?
• Can baldfaced hornets spray venom?

Sources consulted for this fact sheet include the Linnaeus 1763 original description (Centuria Insectorum), NC State University Extension on baldfaced hornets, LSU AgCenter species account, Texas A&M AgriLife Extension Field Guide to Common Texas Insects, peer-reviewed research on nestmate recognition (Ryan et al. 1985), cuticular hydrocarbon studies (Butts et al. 1991), the Maculatic Acids paper (Ren et al. 2018, Angewandte Chemie), and the Schmidt Sting Pain Index (Schmidt, The Sting of the Wild, 2016). Documented colony sizes are from Akre et al. 1981 USDA Yellowjackets of North America handbook.