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14.7: Vespula pensylvanica: Yellowjacket Wasp

Difficulty Level: At Grade Created by: CK-12
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Common Name

  • Yellowjacket Wasp
  • Western Yellowjacket


A yellowjacket wasp is 12 mm (0.75 in.) long. They appear black and yellow, or black and white. The wasp is equipped with a stinger located on the abdomen, and they have antennas on their head. Yellowjacket wasps have six legs, each one as useful as the next. Four wings attached to the wasp's back enable it to swing easily through obstacles, such as humans, cars, bikes, trees, and more. They may build their nests close to humans, but most colonies only stay active one year. Yellowjacket wasps have been symbols all the way back to their discovery. For example, the yellowjacket is the most popular mascot of Georgia Tech, where his name is Buzz. Be careful about handling dead wasps, because they can still sting once deceased, but only for a certain amount of time.

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Hymenoptera
  • Family: Vespidae
  • Genus: Vespula
  • Species: Vespula pensylvanica


Yellowjackets range across North America. The yellowjacket can live in lawns, the base of tree shrubs, attics, the walls of houses, and storage buildings. The wasp is able to live above and below the ground, and tends to live around meadows, as well as the edge of forests. All yellowjackets live in either colonies, nests suspended from trees, or on the corners of buildings. They can be seen during the late spring, summer, and the early fall. Their nest is made of paper, which is gathered off trees. They then mix it with their saliva and use it to build the nest. Underground nests can be destroyed due to flooding.

Cell Biology

A cell is the tiniest structural and functional part of an organism. New cells come from existing cells. Yellowjacket cells are so small that you can’t see them without the help of a microscope, and to be able to see the tiny structures that roam inside of the cells, you need another special type of microscope, an electron microscope. Then you are ready to explore the inside of a cell. Each individual cell in a yellow jacket's body is made for a certain task. For instance, red blood cells are shaped with a pocket that encloses oxygen, and carries it to other body cells. Then there are nerve cells, which are long and stringy, so that they can form a line of communication with other nerve cells, like a wire. Because of their shape, they can quickly send signals. Cells are shaped in ways that help them do their tasks. Yellowjackets are multicellular organisms and have many types of specialized cells in them.


The yellowjacket wasp didn’t evolve from honey bees, even though it has been said before. The reason that’s been said before is because honey bees and yellow jackets do have a similar ancestor in their background. But they’re neither a bee nor ant. Yellowjackets evolved several traits before vertebrates (animals characterized by a segmented spinal column and a differentiated head) even appeared. These traits are found in most animals. The first yellowjacket trait to evolve was “multicellularity”, a highly adaptive change. Many cells can do different jobs. They can make special changes that enable them to do their work very well. However, the first invertebrates still needed tissues. Sponges are the first organism at the multicellular stage of invertebrate evolution.

Living cnidarians (invertebrate animals of the phylum Cnidaria) like jellyfish, are the next part of invertebrate evolution. This was the first step in the evolution of organs and organ systems. At first, invertebrates created tissues from just two embryonic cell layers. There was an outer cell layer called “ectoderm” and an inner cell called “endoderm”. Both cell layers allow different kinds of tissue to form.

A trait that evolved very early is symmetry. A sponge doesn’t have symmetry. This means that it can’t be cut in two identical halves. The coral polyp and the beetle have symmetry. The coral polyp has radial symmetry, which was the first type of symmetry to evolve. The coral has a distinct top, as well as bottom, but not distinct ends. It can be split into equal halves like a pie, but not in right and left halves. Animals that have radial symmetry have no sense of direction, which makes controlled movement impossible.

Flatworms are the next level of invertebrate evolution. They evolved cephalization, which is adaptive and gives control of the whole organism. Cephalization was the first part in the evolution of a brain.

Cephalization created bilateral symmetry. This allows the animal to tell the difference between different movements, which is of course it needs to control its direction.

Ancestors of the flatworms also evolved a mesoderm. The mesoderm is the last layer of cells that are in middle of the ectoderm and the endoderm. The evolution of this new cell layer lets animals make new tissues such as muscle.

Early invertebrates didn’t have a digestive system. There was only one opening for the mouth and anus. The first roundworms were the start of animals developing a complete digestive system. They had a separate mouth and anus, which allowed food to go through the body in a single direction. This all made up the evolution of the digestive system.

The first roundworms evolved a pseudocoelom. This is a body cavity that is full of liquids. It gives space for the inner organs to develop.

Segmentation evolved next. This is the body breaking up into many parts. The earthworm and the ant both have segmented bodies, which gives them more flexibility. This also gives them better movement. All arthropods also evolved jointed appendages. For example, they evolved jointed legs for walking, and antennas.


These types of wasps mainly feed on other insects, and a common favorite is flies. Yellowjacket wasps eat spiders and insects, as well as human food. The human food diet includes meats, sweets, picnic trash, bird feeder seeds, sodas, and fruits. Many adults eat nectar, and larvae feed on pre-chewed food. They look for sources of food within a mile of the nest. They don’t leave stingers in skin, unlike bees. The stinger goes in smoothly, so they can sting a person multiple times. The yellow jacket's nest is very easy to see if you’re outside, and hard to see if you’re inside. You can sometimes hear them in the walls of complexes, if they have built a nest there. Yellow jackets are attracted to perfumes and fragrances based on a flower odor. If a scent smells like a flower, then they naturally follow the scent. Some fly species try to mimic the yellowjackets, by having the same colours, or stripes as them, in order to create the same fear that wasps give, and be left alone. Most people are fooled by their disguise. A full yellowjacket nest can have up to 600-800 workers.

Anatomy and Physiology

Yellowjackets don’t have red blood like humans. Their blood, which is called the hemolymph, is colorless and very different from the blood of humans. Human blood and yellowjacket blood, both are water reservoirs, and bring nutrients, waste, and hormones. Their blood has no oxygen flowing through it, unlike humans. A yellow jacket's heart is located in the back of their abdomen, whereas humans have their hearts in the front of their chest. The heart of a yellow jacket also has little importance. They don’t need it to flow blood throughout their body. Blood squeezes through the inner parts of the insect, throughout the body.


Unlike bees, the yellowjacket wasp does not produce honey. Yellowjackets are social wasps, which means they live in hives or wasp communities. The queen wasp lays all the eggs, so she keeps the workers from laying eggs. In the spring, females create a tiny nest and bring food daily to the larvae in it until it grows up. Females serve as workers, increasing the nest size and caring for the young. In the summer, the males have unfertilized eggs and mate. After the cold weather comes in, all yellowjackets die except for mated females.




  • Zion Lynch

Supervising Faculty

  • Amy Huff Shah


  • Museum School, San Diego, California


  • Published prior to review.

Edit History

  • Created: April 5, 2013
  • Version 1.0 submitted to CK-12: July 11, 2013
  • CK-12 edits: in progress


  • Middle School (grades 6-8)

Opening image copyright by Lara Zanarini, 2013. Used under license from Shutterstock.com.

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