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Western Yellowjacket

Vespula pensylvanica[8][1]

Yellowjackets are social wasps that nest mostly in the ground and in wall voids, defend their nests vigorously, and become persistent scavengers at picnics and garbage cans in late summer and fall.[1][2]

Group
Insect
Order
Hymenoptera
Family
Vespidae
US records
51 states
Sources
8 cited
Updated
2026-10-14
Western yellowjacket worker on gravel, black with bright yellow bands
Western yellowjacket worker on gravel, black with bright yellow bands. (c) eebee, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0
On this page
  1. Identification
  2. Look-alikes
  3. Where it lives
  4. Biology
  5. Damage and signs
  6. Health risk
  7. Control
  8. Related profiles
  9. Common questions
  10. Sources

How to identify it

  • Medium-sized wasps, black with jagged bands of bright yellow on the abdomen and a very short, narrow waist.[1]
  • In flight they hold their legs close to the body, unlike paper wasps, which dangle their legs.[3]
  • Nests are paper, built in rodent burrows, under rocks and landscape timbers, or in walls, attics and crawl spaces, enclosed in a paper envelope with a single entrance.[1][2]

Look-alikes

Look-alikeHow to tell them apart
European paper waspLarger and slimmer, with a thinner waist, orange-tipped antennae and dangling legs in flight; builds open, umbrella-shaped nests.[3]
Honey beeHairy and golden brown rather than shiny black and yellow; UK Entomology rates yellowjackets as more dangerous and unpredictable than honey bees.[2][4]
Bald-faced hornetBlack and white instead of black and yellow, larger, and builds football-shaped aerial nests.[2]
Eastern yellowjacketThe common ground-nesting yellowjacket of the eastern US has a wide, anchor-shaped black mark on the first abdominal segment.[5]
German yellowjacketThis invasive northern species has a small spade-shaped mark on the first segment, black spots down the sides, and often nests in walls.[6]
Southern yellowjacketIts workers are yellow and black, but its queens are much larger, about 3/4 inch, and burnt orange.[7]

Where it lives

Common across North America; the western yellowjacket is the species most often encountered in western states. Most nests are in the ground, often in old rodent burrows, but some species nest in wall and ceiling voids.[1][2]

US map: public records from 51 states since 1990 (GBIF).

Biology and life cycle

A queen that mated the previous fall starts each nest alone in spring; colonies reach 1,500 to 15,000 wasps depending on species.[1]

From spring to midsummer workers hunt insects for protein; by late summer colonies need sugar, so workers scavenge sweets, meat and garbage.[1][2]

Colonies usually die out in winter, though some in mild climates survive several years and grow very large.[1][2]

Yellowjacket stingers have no barbs, so a single wasp can sting repeatedly.[1]

Damage and signs

  • Nests in walls can produce a wet spot that becomes a hole as the wasps enlarge their cavity.[1]

Health risk

Stings range from short-term pain to swelling or life-threatening allergic reactions; multiple stings can damage the kidneys and need medical care. Allergic reactions to wasp and hornet stings account for about 225,000 U.S. emergency room visits a year.[1][2]

Control

Prevention

Keep food, drinks, pet food and garbage covered or indoors when wasps are around, and check open soda cans before drinking.[1][2]

Traps and physical control

Lure traps (heptyl butyrate) reduce western yellowjacket foragers but don't eliminate large populations; place them away from patios, between the area to protect and nesting areas. Water traps with protein bait work best for queens in late winter and early spring.[1]

Pesticides

Folk remedies like gasoline or flooding nests seldom work and can lead to many stings.[2]

When to call a professional

If a nest must be removed, the safest course is professional help; wasps attack when they sense spray on their nest, and stings are likely even at night.[1][2]

Don't seal the entrance of a nest behind siding; trapped wasps may chew inward and come out indoors.[2]

Common questions

Why are yellowjackets so aggressive in late summer?
Colonies are at their largest and food is scarce, so workers scavenge sweets and meat at picnics and defend nests more vigorously.[1][2]
Can a yellowjacket sting more than once?
Yes. Their stingers have no barbs, so they can sting repeatedly.[1]

Sources

  1. University of California Statewide IPM Program, “Pest Notes: Yellowjackets and Other Social Wasps, Publication 7450 (March 2012).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnyellowjackets.pdf (accessed 2026-10-06)
  2. University of Kentucky Entomology, “ENTFACT-620: Controlling Wasps, Hornets, and Yellowjackets.” entomology.mgcafe.uky.edu/ef620 (accessed 2026-10-06)
  3. Penn State Extension, “European Paper Wasp.” extension.psu.edu/european-paper-wasp (accessed 2026-10-06)
  4. University of Kentucky Entomology, “ENTFACT-606: Controlling Nuisance Honey Bees.” entomology.mgcafe.uky.edu/ef606 (accessed 2026-10-06)
  5. Penn State Extension, “Eastern Yellowjacket.” extension.psu.edu/eastern-yellowjacket (accessed 2026-10-14)
  6. Penn State Extension, “German Yellowjackets.” extension.psu.edu/german-yellowjackets (accessed 2026-10-14)
  7. Mississippi State University Extension Service, “Southern Yellowjackets (Bug's Eye View, Vol. 2, No. 32).” extension.msstate.edu/taxonomy/term/4171/2016/southern-yellowjackets-vol-2-no-32 (accessed 2026-10-14)
  8. iNaturalist, “Vespula pensylvanica taxon page (order and family).” www.inaturalist.org/taxa/61355 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.