Wasps And Yellowjackets

The term ‘yellowjacket’ is a phrase often used in the USA in reference to the type of yellow and black striped wasps that is sometimes an unwanted visitor to picnic tables.

However, the world of wasps is incredibly rich and diverse, and even with yellowjackets, it’s a little more complex than that, since it includes two genera (wasp types) and multiple species, rather than one particular species.

Here we will look at broad characteristics and ecology of some of the species of wasps that fall into the category ‘yellowjacket’.

Yellowjacket wasp - Vespula speciesThe common wasp Vespula vulgaris belongs in the category 'yellowjacet' - among others.

Quick Facts About Yellowjackets

  • Yellowjackets include species within 2 wasp genera, and both genera belong in the wasp family Vespidae.

  • Some yellowjackets are aerial nesters, others are cavity nesters.

  • Whilst yellowjackets are commonly thought of as unwelcome scavengers at refuse sites, outdoor eating venues and picnics, not all yellowjackets exhibit such behaviour1, and some – for example, the Bald-faced hornet, are predators of other yellowjackets2.

  • In entomology, the term ‘yellowjacket’ is one word, although it is sometimes seen written as two.

What Is A Yellowjacket Wasp?

Bald-faced hornets are a type of yellowjacket wasp.  This one gathers slithers of wood for nest buildingDolichovespula maculata despite the common name of 'Bald-faced hornet', are a actually a type of yellowjacket wasp.

A yellowjacket wasp is any wasp which belongs to either one of two wasp genera: Vespula and Dolichovespula1

Interestingly, the term ‘yellowjacket’ also therefore includes the black and white Bald-faced hornet, which is in fact a wasp of the genus Dolichovespula rather than a true hornet3.

Likewise, a Vespula species, Vespula consobrina, is also black and white and is commonly called a 'Blackjacket'.

There are 19 species of yellowjackets in North America, 13 of which are Vespula species, the other 6 belonging to the genus Dolichovespula1

Both Vespula and Dolichovespula construct nest cells from tiny slithers of layered wood and plant mattered gathered initially by the colony foundress, and then by workers. 

Eggs are laid by the queen in hexagonal cells very much resembling the hexagonal cells of honeycomb made by honey bees (Apis species).


ground nest of a yellowjacket Vespula speciesEntrance to the ground nest of yellowjacket of the Vespula genus

Vespula are cavity nesters.  A suitable cavity could be underground, for example an abandoned, underground rodent hole or tree root cavity. 

Alternatively, suitable cavities might be found in a roof space, a wall cavity, or even, as author of 'Wasps – The Astonishing Diversity Of A Misunderstood Insect', entomologist Eric R Heaton notes, the interior of a derelict vehicle4.

Whilst colonies of some yellowjacket species only last until autumn (after which, the colony will die and only new queens survive), in warmer regions, nests of some species can be perennial, each year growing ever larger until a nest becomes vast1 (see the table below).

A number of species are scavengers1, meaning they are  adaptable and opportunistic in their food gathering habits.  

This basically means that in addition to taking invertebrates and their larvae to feed to their own offspring, they will also seek to scavenge on human food waste, and at other resources, such as ripe fruit. 

This behaviour may of course, raise concern among humans – see my advice about deterring wasps.

Other Vespula species are predators only, seeking out protein in the form of other invertebrates, and typically are less likely to visit places occupied by humans1.

The table below provides an overview of the colony characteristics and feeding behaviours of various Vespula species (adapted from Reed & Landolt1).

Vespula species
(and common name)
Colony SizeColony Decline*

Vespula germanica
(German yellowjacket)
and scavengers
500–5,000 workersLate September
to early December
Vespula maculifrons
(Eastern yellowjacket)
500–15,000 cells
Vespula pensylvanica
(Western yellowjacket)
Perennial colonies
Vespula alascensis
(Common yellowjacket)
100,000+ workers
Vespula flavopilosa
(Downy yellowjacket)
1 million cells
Vespula vulgaris
(Common wasp)
50,000–100,000 workers have been found in
southern California, but in cooler climates,
colony sizes are much smaller, typically
fewer than 1,000 workers.
Vespula squamosa
(Southern yellowjacket)
Predators and
some scavengers
500–4,000 workersLate August
to November
500–10,000 cells
Vespula sulphurea
(California yellowjacket)
Some perennial colonies
Vespula atropilosa
(Prairie yellowjacket)
Strictly predators75–400 workersLate August
to September
Vespula acadica
(Forest yellowjacket)
500–2,500 cells
Vespula consobrina
No perennial colonies
* The period when reproductives emerge.


yellowjacket aerial nest of a Dolichovespula wasp speciesYellowjacket wasps of the Dolichovespula typically suspend their nests from tree branches, buildings, or are found in shrubs.

Dolichovespula are aerial nesters. 

Nests are typically found hanging from the branches of trees and inside shrubs, (and are often found in forests) but they may also be seen attached to buildings.

They typically start out as approximately egg-shaped, with an entrance hole at the bottom of the nest.

The table below provides an overview of the colony characteristics and feeding behaviours of two Dolichovespula species (adapted from Reed & Landolt1).

Dolichovespula species
(and common name)
Colony SizeColony Decline
Dolichovespula arenaria
(Common aerial yellowjacket)
100–700 workersEarly July
to September
500–4,500 cells
Dolichovespula maculata
(Bald-faced hornet)
No perennial

Yellowjacket Predators

All yellowjacket species may be predated upon by birds (such as the bee-eater) and animals, as well as other invertebrates, including other wasps.

They are also attacked by other parasitoid wasps, such as a genus of wasps called Bareogonalos4. 

Most Bareogonalos are hyperparasitoids (i.e. they develop as hyperparasitoids in parasitoid wasps) which completes its lifecycle in yellowjackets and hornets4.

For example, a Bareogonalos species may lay more than 2,000 eggs on the leaves of plants, which are subsequently eaten by caterpillars. Yellowjackets or hornets may then feed the infected caterpillars to their own larvae, thus infecting their offspring with the parasite5.


1.    Reed, Hal C. and Peter Landolt. “Ants, Wasps, and Bees (Hymenoptera).” Medical and Veterinary Entomology (2019): n. pag.

2.    Enroth, Chris. Baldfaced Hornet: Dangerous bug or beneficial insect? University of Illinois Extension, College of Agricultural, Consumer & Environmental Sciences, February 2022 (Article).

3.    Baldfaced Hornet (psu.edu)

4.    Eric R. Heaton; Wasps – The Astonishing Diversity Of A Misunderstood Insect, Princeton University Press 2021.

5. Chang-Jun K, Jiang-Li T, Bong-Woo L, Seung-Hwan O, Moon-Bo C, Discovery of a trigonalid wasp, Bareogonalos xibeidai (Hymenoptera: Trigonalidae), reared from nests of Vespula koreensis koreensis (Hymenoptera: Vespidae) in South Korea, Journal of Asia-Pacific Biodiversity, https://doi.org/10.1016/j.japb.2020.06.006.

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