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Wicked Wasps

During the spring, you’ve probably witnessed the beauty of nature. The flowers bloom, the butterflies flutter around, and the trees sport lush green leaves. You’re on a walk in the park when you suddenly feel a painful sting on your leg. The beautiful scene is shattered as you come face to face with a German yellowjacket wasp.

These black-and-yellow-striped invasive insects seem to emerge in huge. amounts during the spring, attacking you for seemingly no reason as you try to enjoy your day. Now, you are faced with a painful sting that leaves behind swelling, itching, redness, and, in extreme cases, nausea and fatigue. An irritating sting is left behind to remind you of the yellowjacket wasps’ unanticipated quarrel with you.



There are many species of yellowjacket wasps, many of which are native to North America such as the North American yellowjacket, Eastern yellowjacket, Western yellowjacket, and Prairie yellowjacket. However, the German yellowjacket is one of many invasive species brought over from Europe, Asia, or North Africa.

German yellowjackets first came to Canada in the 1960s. Later, they spread to the Northeastern United States in the 1970s and to the Pacific Northwest United States in the 1980s. These invasive insects then spread down the Eastern coast, where they reached Southern California in 1991 and established themselves as part of California’s ecosystem.

The German yellowjacket integrated itself so forcefully into the Californian ecosystem that it is now far more common than any other yellowjacket wasp species in urban California.

Nowadays, German yellowjacket wasps can be found all over the world, including in Chile, Argentina, New Zealand, and Australia. Unlike other yellowjacket species, these invasive German yellowjackets are usually regarded as pests.


In the United States, German yellowjackets are typically found in California and the Northeastern US. German yellowjackets typically build their nests in protected areas where the temperature will not limit their survival, which has led to many nests being built in buildings. German yellowjacket wasps may be found in the ground in burrows, a building’s walls, or the attic of a house.

In Washington D.C., there was one nest found in an attic that measured 5 feet wide and 3 feet deep. Some German yellowjackets in areas such as New Zealand prefer to build their nests in the ground, as shown by a long-standing 14-foot-long and 5-foot-wide nest excavated in New Zealand’s ground. The proximity of the nests of these pests makes German yellowjackets a public health risk.

These social wasps are particularly numerous in the summer because the life cycle of a German yellowjacket wasp colony includes a queen first finding a structurally sound cavity to survive the winter alone, and then starting a new colony in the springtime.

The queen will birth eggs and fertilize some of them to become female German yellowjacket wasps and leave some unfertilized to become male. The queen wasp tends to her first group of worker wasps but later becomes bound to the nest to increase the size of the colony. These wasps grow in population at such a fast rate that by July or August, there may be 4,000 wasps or more within a nest that can span more than 2 feet wide.

Dangers of Sting Reactions

Like most insects, German yellowjackets are mainly interested in protecting their nest or home. However, German yellowjackets can be said to take this protective need to an extreme. German yellowjackets will attack you if you come within even a few feet of their nest unsuspectingly.

When these wasps sting, they inject venomous fluid under the skin that can cause symptoms such as painful swelling, itching, redness, nausea, and fatigue in typical situations. To make it all worse, German yellowjackets have smooth stingers and can therefore sting multiple times, unlike our beloved honeybees, which die after stinging you once.

Severely allergic individuals may have extreme reactions to German yellowjacket stings, however, no deaths have been attributed to the stings as of yet. Allergic reactions occur in individuals who have developed the antibody immunoglobulin E after a previous sting from the same type of insect venom. Allergic reactions may be mildly skin irritating or life-threatening, and can include swollen red bumps and flushing of the skin, or difficulty breathing due to pharynx epiglottis swelling or bronchial passage narrowing.

Anaphylaxis is the most severe allergic reaction that may occur as a result of German yellowjacket stings. Anaphylaxis commonly occurs more often in males and individuals under 20 years of age. Severe allergic reactions can also include hypotension (low blood pressure, disturbances in blood circulation, and difficulty breathing) that can become cardiorespiratory arrest, which may be fatal. Most people who develop anaphylactic reactions to German yellowjackets have previously experienced yellowjacket wasp stings with little issue, but there is over a 50% risk of having a recurrent episode if anaphylaxis has already occurred.

Less than 1% of all German yellowjacket sting reactions occur days or weeks after the initial sting. These delayed reactions may include symptoms of brain inflammation (encephalitis), nerve inflammation (neuritis), blood vessel inflammation, kidney inflammation, and blood clotting disturbances.

To pair with delayed reactions, allergic reactions, and typical reactions, there is also the issue of toxic reactions to multiple German yellowjacket wasp stings. Toxic reactions occur as a result of a mass amount of toxic venom within the blood of an individual rather than an immune response such as the other reactions. Symptoms of a toxic reaction can include fever, diarrhea, nausea, headache, vomiting, convulsions, and fainting. Swollen red bumps or a rash and other skin-related symptoms are possible in toxic reactions, however, they are much more common in allergic reactions to German yellowjacket stings.

Secondary bacterial infections from German yellowjacket sting sites are also not uncommon, as bacteria can develop in an untreated, uncleaned sting site.

As can be seen by all the possible reactions to the sting of a German yellowjacket wasp, these wasps can be considered dangerous to people.

Environmental Impact

German yellowjackets are slowly but surely damaging our environment. Just by being an invasive species that is more aggressive than native yellowjacket species in the United States, these German yellowjackets are slowly taking the place of native yellowjacket wasps in our ecosystems.

To add to this, these German yellowjacket nests release foul odors that attract flies and other scavenger insects to houses and buildings, which prevents these insects from performing their natural duty to break down organic materials and pollinate plants. German yellowjackets are also naturally carnivorous, so they will eat all these flies that are attracted to the nests and will even eat bees, which lowers the insect population that pollinates flowers, a crucial part of our ecosystem.

Although German yellowjackets do also feast on flower nectar and sweet foods such as fruit, this too comes with its own negative effects, as these pests will attack people to obtain these foods. German yellowjackets are known to harass people at picnics, in bakeries, at candy factories, in stadiums to eat their spilled sodas, at theme parks, and more.

To make it all worse, German yellowjackets often travel in packs, so if you are attacked by one wasp, it is likely all the wasps will attack. This can lead to multiple stings with a mass amount of venom, which can be extremely damaging to your health.

Eradication of these active nests is difficult and costly, but necessary to prevent these scavenger insects from harassing humans, eating pollinators such as bees and flies, and emitting a foul odor that disrupts the natural order of the ecosystem.


To exterminate German yellowjackets, the only real option is to contact a professional pest control service. With German yellowjackets, plugging the nest entrance does not work because they are known to chew through the wood and interior wall coverings of the plugs to escape. If successful, German yellowjacket wasps will enter the living area of your home once they’ve chewed through the wall.

Even spraying insecticide inside the nest proves futile in some cases, as these insects can just chew through the walls to escape the poisoned nest. Ridding yourself of these pests is extremely difficult such that the only option is to contact a professional pest management company to remove the nest.

In the future, we may come up with more effective methods of reducing the population of German yellowjacket wasps as more research is conducted. At UC Riverside, research has shown that a synthetic chemical lure in traps can be used to detect these pests and determine if they will become troublesome. Research to develop area-wide baiting programs that are safe and effective is also being conducted. Pesticides have also been tested for their ability to deter yellowjackets. Many research studies are currently being conducted such that if research into deterring and reducing this invasive species’ population proves fruitful, extermination in the future may be more effective and straightforward.



German yellowjackets are an invasive species that entered the United States in the 1970s from either Europe, Northern Africa, or Asia. These aggressive wasps are known to cause a variety of health issues with their stings, such as toxic reactions, allergic reactions, secondary bacterial infections, and typical reactions.

German yellowjackets, often emerging in the summer, harass people and are known to damage the ecosystem by taking the place of native yellowjacket wasps and eating pollinators such as bees and flies. These pests often reside in attics, burrows in the ground, or a building’s walls. They are extremely difficult to remove from our ecosystem due to their ability to chew through wood and their nests in the event that their nest is compromised by pesticides. All in all, German yellowjackets are a danger to the people, our ecosystem, and the United States.

If you liked this blog and want to learn more about other invasive species, check out our Medium profile. Stay updated and active by following the Environmental Defense Initiative on Medium and all of our social media platforms!

Author: Karen Wong

Editor: Charlotte Wang


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