Critter Catalog

What do they look like?

Bald-faced hornets get their name from the white spots on the face, legs, thorax, and abdomen. The rest of the body is dark black. They have two dark wings and brown eyes. Bald-faced hornets are the largest species in the Dolichovespula genus. Workers are 12-14 mm long, while queens are 18-20 mm long. Males have white markings on the first segment of the abdomen. They have 7-segmented abdomens and 13-segmented antennae. Females have 6-segmented abdomens and 12-segmented antennae. Bald-faced hornets have a painful, venomous sting. (Buck, et al., 2008; Jacobs, 2015)

• Other Physical Features
• ectothermic
• bilateral symmetry
• venomous

• Sexual Dimorphism
• female larger
• sexes colored or patterned differently

• Range length

  13 to 20 mm

  0.51 to 0.79 in

Where do they live?

Bald-faced hornets, (Dolichovespula maculata), are a species of wasp. They belong to the group of bees known as yellow-jackets. They are found across the United States and Canada, except for the driest parts of the Great Plains region. (Buck, et al., 2008; Jacobs, 2015)

• Biogeographic Regions
• nearctic

What kind of habitat do they need?

The gray, papery nests of bald-faced hornets are aerial. They are built above the ground in trees, bushes, and shrubbery. Nests can also be found on rocks and man-made structures. The large nests are spherical or egg-shaped. They are up to 60 cm in height and 45 cm across. Bald-faced hornets are common on flowers. (Jacobs, 2015; Mullen and Durden, 2019)

• These animals are found in the following types of habitat
• temperate

• Terrestrial Biomes
• forest

• Range elevation

  1 to 20 m

  3.28 to 65.62 ft

How do they grow?

Bald-faced hornets undergo complete metamorphosis like other bees in the order Hymenoptera. Larvae hatch from an egg, then pass through several stages of growth. Once the larvae have fully matured, they begin the pupal stage. During this phase, pupae transform into adult bees. (Foster, et al., 2001; Jacobs, 2015)

• Development - Life Cycle
• metamorphosis

How do they reproduce?

Bald-faced hornets are found in colonies, each with one queen. Queens produce the most offspring, but the female workers can produce a few male offspring. The wasps have different roles in raising young. The workers care for the young and the offspring help the parents. (Foster, et al., 2001; Mullen and Durden, 2019)

• Mating System
• eusocial

New queens and males are produced during the late summer to autumn. They leave the nest and mate after they are fully grown. Most queens in the genus Dolichovespula mate only once. Males die after mating. After storing the sperm, the queens seek out a place to wait out the winter. In the spring, they craft a nest and lay their first brood of eggs. Eggs fertilized by the queen produce female bees, while unfertilized eggs produce male bees. (Foster, et al., 2001)

Female workers are able to produce male offspring. Conflicts between queens and workers over male production are common. Nests with no queen have been reported, which may be due to the workers killing the queen. (Foster, et al., 2001)

• Key Reproductive Features
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• parthenogenic
• sexual
• fertilization
  • internal
• oviparous
• sperm-storing
• delayed fertilization

• How often does reproduction occur?

  Bald-faced hornet queens breed once yearly.

• Breeding season

  Dolichovespula maculata queens and males mate during summer to early fall.

• Range eggs per season

  100 to 400

Fertilized queens build nests during the spring. The queens deposit their eggs and feed the larvae once they hatch. The first group of offspring builds and protects the nest, gathers food, and tends to the new larvae. (Foster, et al., 2001; Jacobs, 2015)

• Parental Investment
• female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

How long do they live?

Queens and males hatch in the late summer to early fall, pupate, then fly off to mate. Males die soon after mating. The fertilized queens find shelter and wait out the winter. In the spring, the adult queens begin to build their nests and lay their first group of eggs. These eggs become workers after hatching. The second group of eggs includes the males and new queens. The original queen will die with the rest of the nest during autumn, while the new queens live through the winter. (Foster, et al., 2001; Jacobs, 2015)

• Range lifespan
  Status: wild

  1 (high) years

How do they behave?

Bald-faced hornets are a colonial species. Despite their large size, they are less aggressive than some smaller species of yellowjacket. Each nest is created by a dominant queen bee that produces most of the offspring. The queen chews fibers from old wood and adds her saliva, making a paste. The paste dries into the papery material that makes up the nest. (Arnett, 2000; Buck, et al., 2008; Mullen and Durden, 2019)

• Key Behaviors
• flies
• motile
• social
• colonial
• dominance hierarchies

How do they communicate with each other?

Like other social bees, bald-faced hornets communicate using touch, vision, chemicals called pheromones, and wing vibrations. Bees communicate about the safety of the nest, where food is, and what they should do. Like other bees, bald-faced hornets can see ultraviolet light.

• Communication Channels
• visual
• tactile
• acoustic
• chemical

• Other Communication Modes
• pheromones
• vibrations

• Perception Channels
• visual
• infrared/heat
• ultraviolet
• tactile
• acoustic
• vibrations
• chemical

What do they eat?

Bald-faced hornets are predators of insects, including arthropods, flies, and other yellow-jackets. They also feed on pollen, nectar, and fruits. (Buck, et al., 2008; Mullen and Durden, 2019)

• Primary Diet
• omnivore

• Animal Foods
• insects

• Plant Foods
• fruit
• nectar

What eats them and how do they avoid being eaten?

Bald-faced hornets have a venomous stinger that they use to attack. Their stings are painful and are used to defend themselves and their nests (Mullen and Durden, 2019)

What roles do they have in the ecosystem?

Bald-faced hornets are important pollinators that play a big role in the survival of their ecosystems. In addition to pollinating, they eat other types of insects. Bee moths are known to lay their eggs in bald-faced hornet nests. Once the eggs hatch, the larvae will feed on the eggs, larvae, and materials stored by the wasps. (Gambino, 1995)

• Ecosystem Impact
• pollinates

Do they cause problems?

Bald-faced hornets sting to protect themselves. They attack when their nest is disturbed. Large hives may sting many times in a swarm. These bees are able to squirt venom at threats. They are most dangerous to people allergic to bee stings. (Barlett, 2017)

• Ways that these animals might be a problem for humans
• injures humans
  • bites or stings
  • venomous

How do they interact with us?

Bald-faced hornets pollinate flowers while seeking out nectar. Adults mainly eat insects. The large number they eat helps control populations of unwanted insects. (Jacobs, 2015)

• Ways that people benefit from these animals:
• pollinates crops
• controls pest population

Some more information...

Yellow-jacket is an American common name for wasps in the genera Dolichovespula and Vespula. (Mullen and Durden, 2019)

Contributors

Deena Hauze (author), Animal Diversity Web Staff.

References

Arnett, R. 2000. American Insects: A Handbook of the Insects of America North of Mexico. Boca Raton: CRC Press.

Barlett, T. 2017. "Species Dolichovespula maculata - Bald-faced Hornet" (On-line). BugGuide. Accessed May 09, 2020 at https://bugguide.net/node/view/2890.

Buck, M., S. Marshall, D. Cheung. 2008. Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region. Canadian Journal of Arthropod Identification, 5: 492. Accessed May 09, 2020 at http://cjai.biologicalsurvey.ca/bmc_05/bmc_05.html.

Foster, K., F. Ratnieks, N. Gyllenstrand, P. Thorn. 2001. Colony kin structure and male production in Dolichovespula wasps. Molecular Ecology, 10: 1003-1010.

Gambino, P. 1995. Dolichovespula (Hymenoptera: Vespidae), Hosts of Aphomia sociella (L.) (Lepidoptera: Pyralidae). Journal of the New York Entomological Society, 103(2): 165-169.

Jacobs, S. 2015. "Baldfaced Hornet" (On-line). PennState Department of Entomology. Accessed May 09, 2020 at https://ento.psu.edu/extension/factsheets/baldfaced-hornet.

Mullen, G., L. Durden. 2019. Medical and Veterinary Entomology (Third Edition). London: Academic Press.