Red Triangle Slugs Can Indicate Household Mold

Mar 1, 2016

Slugs have a reputation for being nothing more than disgusting pests. Especially if you love to spend time in the garden, you know that slugs have a way of wreaking havoc on your favorite plants. Particularly with bad infestations, slugs can ruin an entire garden if left unchecked. However, it should be noted that slugs also play a very important role in the garden, even if they sometimes get a bit out of hand.

Similar to snails and worms, a slug’s favorite food is decaying organic matter. They may be a bit of an unwelcome sight, but the job they do – particularly in the fall – is vital to a healthy garden and having soil that's rich in nutrients.

Native to Australia, the Triboniophorus graeffei, or red triangle slug, is seen below. It is a very common sight along the country's Eastern coastal regions.

Queensland Museum

It may seem a bit obvious, but the name of this invertebrate comes from the peculiar marking on its back. Though they are called red triangle slugs, the color of the triangle-shaped marking can vary between red, orange, and yellow.


Below, we see another species of slug that is native to Australia. This one goes by the name of Triboniophorus aff. graeffei, but it is commonly known as the pink slug. These slugs used to be considered as being merely a different variety of red triangle slug. However, research has shown that it is most likely a different subspecies altogether.

Michael Murphy/NPWS​​


Between the two varieties of slugs, they share the common characteristic of being air breathers. As seen in the picture below, they have a massive hole in their back through which they breathe.


Aside from how they breathe, the two also share an insatiable hunger for mold, algae, and decaying matter.

Save Our Waterways Now

In Australia, homeowners are quick to dispose of these pests if they ever happen to enter the home. Just like with insects, who would give a second thought to getting rid of them?

Robert Ashdown Photography

It might just be a random occurrence, but special attention must be given to why the slug entered the home in the first place. These animals are always on the hunt for decaying matter, so why would they enter a pristine home?


The answer is mold – their favorite snack. It is far from a sure sign, but the presence of these slugs can be indicative of mold growing in the home. Especially if they are a frequent occurrence, the home should be checked for mold lurking in the walls, floors, and ceilings.

Michael Murphy/NPWS


Though these slugs are only native to Australia, household mold occurs in homes all over the world. It can be a bit difficult to spot, but the presence of mold is often more expansive than what we are able to see on the surface. Below is the area behind a baseboard that would otherwise go unseen.


Mold has been known to cause serious health issues if not addressed. The spores released into the air are irritants to humans and can affect the eyes, skin, nose, throat, and lungs of people who are both mold-allergic and non-allergic. Especially for those who have existing respiratory issues, prolonged exposure can result in dangerous long-term problems.

Hussar Group

According to the United States Environmental Protection Agency, most cases of mold can be dealt with by yourself either by cleaning or completely removing and replacing the affected area. Mold typically grows when there is an abundance of moisture, so special attention should be given to why the mold occurred in the first place. Causes, such as a leaky pipe, should be addressed so that the mold does not reoccur.

Hussar Group

If there's more than 10 square feet of mold or there has been a lot of water damage, it might be time to consider seeking professional help. Even if you are handy enough to deal with a huge teardown project like the one seen below, exposure to the mold and spores can cause numerous health complications. Is saving money really worth the expense of your health?

Hussar Group


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