Why Do Ladybugs Stink? The Reason Behind Their Unpleasant Odor

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Why Do Ladybugs Stink

Have you ever realized that your favorite cute, red, dotted bug is a stinky little bugger? Why do ladybugs stink, and what can you do about it? Let’s find out.

Ladybugs are among the most loved and admired creatures worldwide, primarily because of their colorful bodies and harmless nature. 

However, not many people know that they are also a type of stink bug because they release an unpleasant odor when threatened by a potential predator. 

Intrigued? Read the article to know more. 

Why Do Ladybugs Stink

Why is Ladybug Stink a Problem?

Many people love holding ladybugs and making a wish – they are considered the ultimate symbol of good luck in many cultures. 

If you have ever handled a lady beetle, you might have experienced its stench. After all, you are a huge hairy animal holding the poor thing in your hand.

You have the power to crush it! It’s no wonder that ladybugs consider us as threats. So yes, it immediately brings out its smelly fluid called pyrazine. 

It does so by rubbing its joints or feet when you try to handle it.

The special glands on their feet release this fluid to keep predators from eating them. To a casual observer, it seems as thugh the ladybugs are peeing.

The stinky smell tells predators that eating the bug may not be safe and drives them away. Pyrazine not only smells but also tastes terrible, and thus, is a problem for the predators either way.  

The odor of these stink bugs is so persistent that wineries must take great care when processing and harvesting grapes. 

Why Do Ladybugs Stink

If Asian lady beetles or even native species of ladybugs get crushed with the wine during the process, the end product smells so bad that the whole batch has to be thrown away. 

This effect is known as the ladybug taint, and wine producers take all the measures necessary to avoid attracting ladybugs into the vineyards.

What Does Ladybug Odor Smell Like?

Ladybug odor smells close to a mixture of potato, green bell pepper, and nut and has a moldy odor. 

The mixture at the concentrations in ladybug emissions is referred to as ‘really stinky’ by Lingshuang Cai, and Matthew E. O’Neal, Iowa State University researchers, in a project done in 2006. The next section talks about their research

Testing The Ladybug Stink 

A team of researchers from Iowa State University concluded a study on the chemicals that contribute to ladybug stink

The researchers specifically studied the characteristics of multicolored Asian ladybird beetles that invaded the US in the early last decade. 

The bugs were put in a glass vial for a day to collect the released chemicals from their bodies. 

The team then used chromatography and mass spectrometry to separate and identify the chemicals. 

The study was completed when a panel sniffed the chemicals and concluded the main chemicals responsible for releasing the noxious odor:

  • 3-methoxypyrazine (DMMP), 
  • 2-isopropyl-3-methoxypyrazine (IPMP), 
  • 2-isobutyl-3-methoxypyrazine, 

These chemicals caused the unpleasant odor coming from the bug. The chemicals, when mixed together, create quite a stinky smell.

Why Do Ladybugs Stink

How Do Ladybugs Use This Stink? 

We discussed the defensive aspect of the stinking odor, but there is one more use that ladybugs have for the stench.

Ladybugs use it to mark their territory and let the predators and fellow ladybugs know that the plant ‘belongs’ to its larvae. 

Their feet give off the stink of pyrazine when it is walking after laying eggs on a plant. 

The foul-smelling liquid tells other ladybugs that the plant is already taken and they must find some other place to lay their eggs. 

The odor also keeps native ladybugs away since many of them are cannibals and, thus, won’t shy away from attacking larvae. 

Asian Ladybugs and Their Yellow Secretion?

Asian beetles and ladybugs are not the same even though they belong to the same insect family. 

Ladybugs are beneficial insects that usually mind their own business, especially in winter, when they consider spending their time outside eating pests. 

They are entirely harmless and do not bite human skin. 

Asian lady beetles, on the other hand, are an invasive species that seek shelter inside the warmth of houses during cold weather. 

They can gather in large numbers inside your home and leave yellow stains or secretions on your precious household items, such as furniture, windows, and curtains. 

The Asian lady beetle is also capable of biting human skin and causing reactions in people allergic to bugs and insects. 

They are basically pests that are a nuisance to your house. 

Why Do Ladybugs Stink

Frequently Asked Questions 

Why do ladybugs smell when you squish them?

When you squish ladybugs, they release a chemical called pyrazine which has a stinky odor. 
It works like a defense mechanism for the bug, which signals the predators to think twice before eating the insect. 
Crushing them causes the chemical to come out immediately because they are frightened of you.

How do you get rid of the ladybug smell?

The best way to eliminate the ladybug smell is to clean your hand or the area with soapy water and spray a good freshener. 
You can also install window screens to keep the bugs away from your house in the first place. Also, please make sure you close all wall voids and cracks in windows and door frames.
Ladybugs can enter homes through a gap of less than 1/8th of an inch. Hence you need to be very careful of these cracks.

What are the stinky ladybugs called?

Convergent ladybugs (Hippodamia convergens) from North America are stinky ladybugs that release a foul-smelling chemical to protect themselves from a potential threat or danger. 
Asian ladybeetle, a species not native to America releases a yellow and stinky chemical when frightened as well.

How long do ladybugs live?

On average, ladybugs live for about a year. However, they lay thousands of eggs before their life cycle ends. 
The eggs hatch and multiply quickly, so keeping up with their life cycle is challenging, especially if they settle in for the season. 

Wrap Up 

Ladybugs stink for two reasons – it is a defense mechanism to ward off predators and a way to mark their territory and avoid other ladybugs from coming near their eggs.

The best thing to do in order to avoid the stench is just to let the ladybugs be – they only release these chemicals when they are frightened.

Thank you for reading!

Authors

  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

    View all posts
  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

    View all posts
Tags: Ladybugs

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