Why Do Stink Bugs Even Exist? Discover Their Purpose in the Environment

Written by Heather Hall
Updated: October 19, 2023
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Key Points

  • Stink bugs emit a pungent smell as a defense mechanism.
  • Stink bugs eat plant pests like aphids and caterpillars.
  • There are different species of stink bugs, including the brown marmorated stink bug and the green stink bug.

Stink bugs exist for various reasons, and today, we will discuss them all in detail. We will also help you to tell the difference between beneficial and harmful stink bugs so you know who to keep around.

About Stink Bugs

What Do Stink Bugs Eat - Stink Bug Eating

There are many different types of stink bugs. Some are harmful, and some are beneficial.

©Jay Ondreicka/Shutterstock.com

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Stink bugs are small, shield-shaped insects belonging to the family Pentatomidae. They range in size from 5-20mm and are typically brown or green in color. Stink bugs have six legs and two antennae, and their bodies are segmented into three parts: the head, thorax, and abdomen. They have two large eyes and two smaller ocelli (simple eyes) above them.

Stink bugs are aptly named for their ability to emit a pungent smell when disturbed or threatened. This smell is produced by glands located on the underside of the thorax. The smell is a defense mechanism used to deter potential predators.

Stink bugs eat a variety of plant pests, such as aphids and caterpillars. This helps keep the ecosystem balanced by preventing the overpopulation of these pests. Stink bugs live in gardens, parks, and agricultural fields.

Types of Stink Bugs

Macro image in natural light of isolated specimen of Brown marmorated stink bug, scientific name Halyomorpha halys, photographed on a green leaf with natural background.

The brown marmorated stink bug is not one of the good guys.

©Davide Bonora/Shutterstock.com

Stink bugs are one of the most common types of bugs living in gardens, yards, and fields. There are several species of stink bugs, all of which have their own unique characteristics and behaviors.

The most common type of stink bug is the brown marmorated stink bug (BMSB), which is native to eastern Asia. They are brown in color and have a distinctive shield-like shape, with a flat body and rounded edges. They can grow up to 17mm in length and have a unique smell that is often described as “skunky.” A traveler or shipping container accidentally introduced these bugs to the US in the 1990s, and now they are a permanent resident.

Another type of stink bug is the green stink bug (GSSB), which is native to North America. They are green in color and also have the same shield-like shape as the BMSB but are slightly larger, reaching up to 19mm in length.

The third type of stink bug is the Southern green stink bug (SGSSB), which is native to the southern United States. They are green in color and have a slightly different shape than the other two types, with a more elongated body. They can reach up to 20mm in length and have a less pungent smell than other species of stink bugs.

Stink bugs make their homes in many different areas, including gardens, fields, and forests. They feed on plants, particularly those that produce fruits and vegetables, making them a nuisance for farmers and gardeners alike. Stink bugs are also known to invade homes, where they can become a major nuisance.

Why Stink Bugs Exist — They Eat Harmful Pests

armyworm on leaf

One of the reasons why stink bugs exist is to eat crop pests like the fall

armyworm

.

©kale kkm/Shutterstock.com

Stink bugs are a type of insect that is beneficial to the environment, as they feed on pests and larvae that are considered harmful to crops and other plants. These types of stink bugs benefit gardeners and farmers, as they help reduce the number of pests that would otherwise cause damage to crops.

There are many different species of stink bugs, and each one is known to eat different types of harmful pests and larvae. Some of the most common types of beneficial stink bugs include the Brochyena stink bug and the spined soldier bug.

The spined soldier bug (Podisus maculaventris) is a great example of a beneficial stink bug. It begins its life as a small dark egg, usually in clusters of up to seventy. As it grows and molts, it changes from a basic black and red color to an array of orange, white, black, and red. Generally cannibalistic in its nymph stage, the bug will become mottled brown as an adult. The spined soldier is easily distinguished from regular stink bugs due to its spines on its shoulders and its short, sharp beak compared to the long, thin mouthparts of other stink bugs.

The spined soldier has a great purpose in the environment – they feed on ninety species of caterpillars and beetle larvae. Their strong mouthparts allow them to penetrate their prey and suck out its body juices, eliminating the pest. The bugs are known to consume corn earworms, European corn borers, oleander caterpillars, fall armyworms, and flea beetle larvae. Having these creatures around in your garden is sure to be a benefit!

Why Stink Bugs Exist — They Provide Food

Natterjack Toad eating earthworms.

If you were to ask a toad why stink bugs exist, he would say, “For dinner!”

©Laura Ojalvo Ortega/Shutterstock.com

Stink bugs benefit the environment in many ways, including providing food for other animals, insects, spiders, and mammals. While these insects may be considered a nuisance to humans, they provide a source of sustenance for animals in the wild.

Animals that benefit from stink bugs as a food source include birds, reptiles, and amphibians. Birds, such as swallows, blue jays, and cardinals, are known to eat stink bugs. Reptiles such as lizards and snakes also consume stink bugs, as do amphibians like frogs and toads. Some mammals, like skunks, are also known to eat stink bugs.

Insects, such as dragonflies, ground beetles, and ladybugs, are also known to feast on stink bugs. Spiders, such as jumping spiders, crab spiders, and wolf spiders, are also known to feed on stink bugs.

Why Stink Bugs Exist — They Improve Plants

farm

Stink bugs exist to help plants improve their defense mechanisms.

©Patricia Elaine Thomas/Shutterstock.com

In addition to the animals that hunt stink bugs, other organisms in the environment can benefit from them as well. For example, some plants create new defense mechanisms and adaptations in response to attack by stink bugs. Plants defend themselves by using chemicals as weapons, trapping their attackers, and even attracting natural enemies of their predators.

Stink bugs can also be beneficial to plants in the form of pollination. Stink bugs are known to feed on nectar from certain flowers, and while doing so, they transfer pollen grains between them, helping to further spread the plant species.

What Do Good Stink Bugs Look Like?

Spined Soldier Bug (Podisus maculiventris)

The reason why good stink bugs exist (like this spined soldier bug) is to eat tasty plant pests.

©nrpphoto/iStock via Getty Images

The ‘good’ stink bugs are called predatory stink bugs because they eat common pests, like beetles and caterpillars. You can tell them apart from the other stink bugs in the following ways.

Stink bugs’ eggs are typically barrel-shaped and laid in bunches of 15 to 30 on leaves. The eggs may be gray, gold, or cream-colored, depending on the species. When in the nymph stage, they are smaller than adults and round instead of shield-shaped, with red and black coloration. As they get older, their markings can be white, yellow, tan, or black. Also, they do not have spines and instead only have wing pads instead of full-sized wings.

Spined soldier bugs are around a quarter to a half inch long when adults. They have a flattened, shield-like shape and are light brown. They have one spine on each of their shoulders. Spined soldier bugs also have a yellow beak that they hold under their body.

Two-spotted stink bugs are up to a half-inch long and have a similar shield-like shape. They are black with either red or yellow markings, a Y marking on the back, and two black dash marks behind the head.

Are There Bad Stink Bugs?

Southern green stink bug standing on a leaf. Southern green shield bug sitting on a New Zealand spinach leaf. Close up of southern green stink bug Nezara viridula.

This southern green stink bug eats crops and is not beneficial to have near food gardens.

©V.P.I/Shutterstock.com

Stink bugs are a type of insect that is found all across the world. While some species of stink bugs are beneficial, such as those that help keep pest populations in check, many other species of stink bugs are not beneficial and can be fairly harmful.

The most common type of stink bug that is considered to be a pest is the brown marmorated stink bug (BMSB). This species of stink bug is native to East Asia and was introduced to North America in the late 1990s. It is an agricultural pest, as it feeds on a variety of crops, including apples, peaches, corn, tomatoes, beans, and peppers. It also invades homes and buildings and can become quite annoying.

The green stink bug is another species of stink bug that is considered to be a pest. It is found throughout North America and is a major pest of corn, tomatoes, peppers, cotton, soybeans, and other crops. It is also known to invade homes, much like the brown marmorated stink bug.

The consperse stink bug is another type of stink bug found in North America that is considered to be a pest. It is an agricultural pest, as it feeds on a variety of crops, including potatoes, tomatoes, peppers, cotton, soybeans, and other crops. It is also known to invade homes and buildings, which can be quite annoying.

The red-shouldered stink bug is a species of stink bug found in the southern United States. It is a major pest of a variety of crops, including corn, soybeans, tomatoes, peppers, and other crops. It is also known to invade homes and buildings, much like the other types of stink bugs.

Can Stink Bugs Hurt You?

Florida Predatory Stink Bug - Euthyrhunchus floridanus aka Halloween Bug on Hercules club leaf - bright red and black face pattern on black back of body -

Florida Predatory Stink Bugs are not at all harmful to humans or animals.

©Chase D’animulls/iStock via Getty Images

Are stink bugs dangerous to humans? Despite the intimidating name, these insects cannot bite, sting, or transmit any diseases. Their only downside is the awful smell they emit when disturbed or crushed.

The scent of a stink bug is often compared to the flavor of the herb cilantro; some even say it smells like ammonia, sulfur, or something like spoiled meat. However, some individuals are not able to detect the smell at all!

However, stink bugs can be a nuisance when they invade homes and buildings. They may hide in furniture, curtains, or other fabrics and produce an unpleasant odor. To prevent them from entering your home, you should seal any potential entry points around doors and windows with caulking or weather stripping. It is also important to keep trees trimmed back away from the house, as this will reduce their access to your home.

Summary Table

Type of Stink BugDescriptionBeneficial or Harmful
Brown Marmorated Stink Bug (BMSB)Brown in color, shield-like shape, flat body, rounded edges, up to 17mm in length, unique smell often described as “skunky.”Harmful
Green Stink Bug (GSSB)Green in color, shield-like shape, slightly larger than BMSB, up to 19mm in length.Harmful
Southern Green Stink Bug (SGSSB)Green in color, slightly different shape than other types, more elongated body, up to 20mm in length, less pungent smell than other species.Harmful
Spined Soldier BugStarts as a small dark egg, changes from a basic black and red color to an array of orange, white, black, and red as it grows, becomes mottled brown as an adult, easily distinguished from regular stink bugs due to its spines on its shoulders and its short, sharp beak.Beneficial
Two-Spotted Stink BugUp to a half-inch long, shield-like shape, black with either red or yellow markings, a Y marking on the back, and two black dash marks behind the head.Beneficial

The photo featured at the top of this post is © Chase D'animulls/iStock via Getty Images


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About the Author

Heather Hall is a writer at A-Z Animals, where her primary focus is on plants and animals. Heather has been writing and editing since 2012 and holds a Bachelor of Science in Horticulture. As a resident of the Pacific Northwest, Heather enjoys hiking, gardening, and trail running through the mountains with her dogs.

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