Animal Diversity Web

Ge­o­graphic Range

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

Habi­tat

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)

• Habitat Regions
• temperate

• Terrestrial Biomes
• forest

• Range elevation

  1 to 20 m

  3.28 to 65.62 ft

Phys­i­cal De­scrip­tion

Bald-faced hor­nets get their name from the white mark­ings on the face, legs, tho­rax, and ab­domen. The rest of the body is dark black. They have brown 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. Fe­males have 6-seg­mented ab­domens and 12-seg­mented an­ten­nae, while males have 7-seg­mented ab­domens and 13-seg­mented an­ten­nae. (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

De­vel­op­ment

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

Re­pro­duc­tion

Bald-faced hor­nets are a eu­so­cial species. The queen is fer­tile, while the fe­male work­ers are vary­ing de­grees of ster­ile. Some work­ers may even re­pro­duce. Like many other eu­so­cial species, bald-faced hor­nets are found in colonies and has a re­pro­duc­tive di­vi­sion of labor. The work­ers tend to the young and 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

• Breeding interval

  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

Lifes­pan/Longevity

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

Be­hav­ior

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

Com­mu­ni­ca­tion and Per­cep­tion

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

Food Habits

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

Pre­da­tion

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)

Ecosys­tem Roles

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

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

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)

• Positive Impacts
• pollinates crops
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

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)

• Negative Impacts
• injures humans
  • bites or stings
  • venomous

Other Com­ments

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.