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’.
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).
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).
(and common name)
|Colony Size||Colony Decline*|
|500–5,000 workers||Late September|
to early December
|1 million cells|
|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.
|500–4,000 workers||Late August|
|Some perennial colonies|
|Strictly predators||75–400 workers||Late August|
|No perennial colonies|
|* The period when reproductives emerge.|
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).
(and common name)
|Colony Size||Colony Decline|
(Common aerial yellowjacket)
|100–700 workers||Early July|
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).
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.