Leather Leaf Slug: All You Need to Know in a Nutshell

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Leather Leaf Slugs are a unique type of slug found in various parts of the world, known for their distinct appearance and behavior. These mollusks are often larger than common garden slugs, possessing a leathery texture and vibrant color patterns which make them stand out among other slug species.

Two species of Leather Leaf Slugs, the Cuban slug (Veronicella cubensis) and Sloan’s slug (Veronicella sloanei), are of particular concern to the state of Florida, as their potential establishment could pose a threat to the local ecosystem and agriculture source. Though they may appear fascinating, it’s essential to recognize the potential dangers these creatures can bring and learn how to identify them properly.

Leather Leaf Slug Overview

Veronicellidae Family

Leatherleaf slugs are part of the Veronicellidae family, which is a group of terrestrial slugs. These land slugs are distinct from other families due to their unique features, such as:

  • Soft, leathery body
  • Tentacles that retract completely into the head
  • Presence of a mantle

Some examples of leatherleaf slugs include the Cuban slug (Veronicella cubensis) and Sloan’s slug (Veronicella sloanei).

Mollusca Classification

As members of the gastropoda class, leatherleaf slugs are part of the larger Mollusca phylum. Here is a comparison table of the classification and features of leatherleaf slugs and other related gastropods:

Feature Leatherleaf Slugs Other Gastropods
Habitat Terrestrial Terrestrial, Aquatic
Body Type Soft, leathery Soft, slimy
Tentacles Retractable Varies
Shell Absent or reduced Usually present

Leatherleaf slugs are unique in their soft, leathery appearance and retractable tentacles, setting themselves apart from other gastropods in the Mollusca phylum.

Habitat and Distribution

North and South America

The Leatherleaf Slug is native to the southern regions of the United States, including states like Florida, Louisiana, and Texas. They can also be found in other states such as Alabama, Georgia, Mississippi, North Carolina, Oklahoma, and South Carolina. In South America, they are found in countries like Argentina and Brazil. These slugs prefer the following habitats:

  • Damp areas
  • Forests
  • Gardens
  • Agricultural fields

Invasive Species in Australia

The Leatherleaf Slug is considered an invasive species in Australia. Here’s a comparison of the Leatherleaf Slug’s impact in Australia and the United States:

United States Australia
Native Yes No
Impact Damaging crops Invasive

In Australia, they have been found in regions with warm climates and create damaging effects on local ecosystems by competing with native species for resources. Preventing their spread is critical to the preservation of native habitats.

Biology and Behavior

Nocturnal Activity

Leather Leaf Slugs are nocturnal animals, meaning they are active during the night. During the day, they typically hide under damp, dark hiding spots like:

  • Fallen trees
  • Planks
  • Rocks
  • Boards
  • Flower pots

As they prefer damp areas, it is not unusual to encounter them near the foundations of homes, gardens, and in greenhouses.


Male and female slugs within this species are both capable of reproduction, as they are hermaphroditic. These creatures engage in an intriguing mating behavior to reproduce. Eggs are typically laid in the damp and dark areas they inhabit, further contributing to the growth of their population.

Features Characteristics
Activity Time Nocturnal
Preferred Habitats Damp, hidden areas
Reproduction Hermaphroditic mating
Common Hiding Spots Fallen trees, flower pots, rocks, or boards

Diet and Impact on Agriculture

Plants and Fungi Consumption

Leather Leaf Slugs primarily eat plants and fungi. Examples of plants they consume include:

  • Cabbage
  • Lettuce
  • Tobacco
  • Tomato

This appetite for various plant species makes them a potential threat to agriculture.

Pestiferous and Invasive Species

Although Leather Leaf Slugs also eat other pests like snails, their negative impact on crops outweighs their usefulness. They are considered pestiferous and invasive species. Here’s a comparison of their positive and negative effects on agriculture:

Positive Negative
Eat other pests (e.g. snails) Consume important crops like cabbage, lettuce, tomato, and tobacco
Provide ecological benefits by decomposing plant matter Spread rapidly, making them difficult to control

It’s crucial for farmers to implement effective control measures to minimize the damage caused by Leather Leaf Slugs on their crops.

Identifying Leather Leaf Slugs

Leidyula Floridana

Leidyula Floridana, also known as the Florida Leatherleaf, is a type of slug commonly found in tropical and subtropical regions. To identify this slug, look for the following characteristics:

  • Body color: Yellowish-brown to dark brown
  • Length: 7–10 cm when fully extended
  • Distinctive feature: A rounded hump near the head

Belocaulus Angustipes

The Belocaulus Angustipes, or Black Velvet Leatherleaf, is another slug species found in moist environments. To recognize this slug, note these features:

  • Body color: Black or dark gray
  • Length: Up to 7 cm
  • Distinctive feature: Smooth, velvety texture

Sarasinula Plebeia

Sarasinula Plebeia, also known as the Tropical Leatherleaf, is frequently found in both urban and rural settings. Recognize this slug using the following traits:

  • Body color: Light to dark gray
  • Length: 3–4.5 cm
  • Distinctive feature: Circular groove on the rear part of the body

Here’s a comparison table of these three leather leaf slug species:

Species Body Color Length Distinctive Feature
Leidyula Floridana Yellowish-brown 7–10 cm Rounded hump near the head
Belocaulus Angustipes Black/dark gray Up to 7 cm Smooth velvety texture
Sarasinula Plebeia Light/dark gray 3–4.5 cm Circular groove on rear part

Keep these features in mind when identifying Leather Leaf Slugs, as they will help you distinguish between the different species.

Human Health and Commerce

Rat Lungworm Infection

Leatherleaf slugs can carry the nematode parasites Angiostrongylus cantonensis and Angiostrongylus costaricensis, which cause rat lungworm infection in humans. People can contract this disease by consuming raw or undercooked slugs or vegetables contaminated with these parasites. Symptoms of rat lungworm infection include:

  • Headache
  • Stiff neck
  • Nausea
  • Vomiting
  • Neurological issues

To reduce the risk of infection, it’s essential to properly wash and cook vegetables and avoid consuming raw slugs or snails.

Agricultural Management

Leatherleaf slugs can cause damage to agricultural crops, leading to economic losses. There are various management methods used to control slug populations:

Chemical methods

  • Molluscicides: Effective in reducing slug populations, but may harm non-target organisms and the environment.

Biological methods

  • Predators: Natural enemies like beetles, birds, and nematodes; can help control slugs without harming the environment.
  • Nematode parasites: Phasmarhabditis hermaphrodita specifically targets slugs and can help control their populations.

Physical methods

  • Traps: Beer-baited traps, for example, can catch and drown slugs.
  • Barriers: Copper tape or diatomaceous earth can deter slugs from accessing crop areas.
Methods Pros Cons
Chemical Effective in reducing slug populations May harm non-target organisms and the environment
Biological Environmentally friendly May take longer to see results
Physical Non-toxic and effective Can be labor-intensive

Implementing a combination of these methods can lead to the most effective and sustainable slug population management.

References and Observations

Research by Cowie, Robinson, and Others

Cowie, Robinson, and other researchers have studied various species of leatherleaf slugs, including:

  • Leidyula floridana
  • Belocaulus angustipes
  • Sarasinula plebeia

Their studies provide valuable insights into the behavior, distribution, and impact of these slugs on the ecosystem.

Notable Observations in Different States

  • TN: Smith and Dundee reported the presence of Leidyula floridana in Tennessee.
  • FL: Rambo discovered Belocaulus angustipes in Florida, noting its rapid spread across the state.

Comparison table of slug species:

Slug Species Distribution Example of Observation
Leidyula floridana Tennessee Smith and Dundee
Belocaulus angustipes Florida Rambo
Sarasinula plebeia

Some characteristics of leatherleaf slugs include:

  • Slimy and soft-bodied
  • Lack of an external shell
  • Generally brownish or grayish in color
  • Omnivorous diet, including decaying plant material and fungi

Pros and cons of leatherleaf slugs in the ecosystem:


  • Contribute to nutrient cycling by breaking down organic matter
  • Serve as food for various predators (e.g., birds, small mammals)


  • Can cause damage to ornamental plants and agricultural crops
  • May compete with native slug species for resources

Common Misconceptions

Leather Leaf Slugs and Their Misidentification as Bugs

Leather leaf slugs are often mistaken for bugs due to their appearance. However, they are a type of mollusk, related to clams and oysters. Here are some key differences:

  • Bugs: Insects with six legs and three body parts
  • Slugs: Slimy, soft-bodied mollusks with no legs
Feature Bugs Slugs
Legs Yes, six legs No legs
Body parts Three body parts No distinct body parts
Type Insects Mollusks

People may misidentify them as bugs, leading to confusion when trying to handle or eliminate them.

The Salt Myth

Many people believe that sprinkling salt on slugs is an effective method to kill them. While salt does kill slugs, it is not the best solution for several reasons:

  • Applying salt can increase soil salinity, harming plants.
  • Salt might have negative effects on other organisms in the garden.

Alternative slug control methods include:

  • Hand-picking and destroying slugs
  • Using beer-baited traps
  • Applying diatomaceous earth around plants

In conclusion, understanding the real identity of leather leaf slugs and the drawbacks of using salt to kill them will help you make informed decisions in your garden and protect your plants.

Types and Species

Laevicaulis Alte

Laevicaulis alte is a species of leatherleaf slug native to Africa. It is nocturnal, hiding under wood and crevices during the day1. This slug can be identified by:

  • Grayish or brownish color
  • Soft, slimy body without legs2

Some key features of Laevicaulis alte include:

  • Attraction to moist environments
  • Feeds on dead plant material1

Lesser-Known Species

There are other species of leatherleaf slugs less commonly found, such as Veronicella species1. Due to similarities in appearance, proper identification requires:

  • Taxonomic experts
  • Morphological and molecular methods1
Slug Species Identification Known Habitats
Laevicaulis alte Grayish or brownish, slimy body Africa, gardens & moist areas1
Veronicella species Require expert identification Specific habitats vary1

Overall, it is essential to be aware of the differences between leatherleaf slug species and consult experts for proper identification.

Population and Conservation

Monitoring and Controlling Populations

The Leather Leaf Slug belongs to the family Veronicellidae. It is essential to monitor and control their populations as they can impact agriculture and habitats. For example, reducing humidity in gardens helps control slug populations. High moisture conditions favor slug proliferation.

  • Metaldehyde baits can help control slugs when applied correctly and timely.

Some pros of these baits:

  • Effective in controlling slugs

Some cons include:

  • Baits need careful application
  • Timing is crucial for successful results

Invasion and Its Effects on Ecology

The Leather Leaf Slug can grow up to 120mm in length and is known to invade various habitats, especially those close to water sources. Slug invasions can disrupt ecosystems, affecting both plant and animal populations.

The table below compares the effects of slugs in natural and agricultural habitats:

Habitat Type Effects of Slug Invasion
Natural Disruption of plant and animal life
Agricultural Damage to crops, reduced yield


  1. Entomology and Nematology Department 2 3 4 5 6
  2. UMN Extension

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Leather Leaf Slug from South Africa


Subject: slug
Location: South Africa
March 3, 2014 5:14 am
I recently found this guy cruising around the backyard just before sunrise. I estimate the size to be 8cm long and about 4cm thick. I have never seen slugs like this before. Do you have any idea what type of slug this is?
Signature: Em

Leather Leaf Slug

Dear Em,
Slugs belong to the phyllum Mollusca and most members of the class are univalves and bivalves that live in the water, including snails, clams, oysters and mussels.  Octopi and squid are also molluscs.  Slugs are classified in the class Gastropoda.  The PHotographs of South Africa blog has some images that look similar to your slug, but lacking the stripe down the center of the body.  We are going to try to contact Susan Hewitt to see if she can provide any information.

Thank you very much for the help. I hope she knows and I get to see more – very pretty!

Susan Hewitt responds:  Leather Leaf Slug
Hi Daniel and Em. This rather handsome, large land slug is a “leather leaf” slug in the family Veronicellidae — the mantle completely covers the body. However I don’t know enough to be able to tell you which genus or species it is. It may possibly be an introduced species in your area.

Thanks so much Susan! I do hope to see more around, very unusual slug. Regards.

Letter 2 – Florida Leatherleaf Slug Eggs


Slug or Snail Eggs, Maybe Not?
October 25, 2009
Dear Bug Man,
I’m pretty sure these are not bug eggs, but I am confident you can help ID these things.
I discovered this cluch of eggs under a pile of wet and decaying wood.
Thanks for the help,
W. Matthews
San Antonio, TX

Amphibian Eggs perhaps???
Amphibian Eggs perhaps???

Hi W. Matthews,
We agree they are not insect eggs, and we would also probably discount snail or slug eggs.  We believe they may be Amphibian Eggs, though it is also possible they are some type of fungus or mushroom.  Hopefully one of our readers may supply an answer.

Update:  June 1, 2014
We stand corrected.  Thanks to a new inquiry following a comment from W. Parks, we have learned that this is an egg clutch of the Florida Leatherleaf Slug,
Leidyula floridana.


  • 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.

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  • 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.

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9 Comments. Leave new

  • Those are slug eggs. I have one in a terarrium and they match that completely.

  • Susan J. Hewitt
    March 3, 2014 11:19 am

    Hi Daniel and Em. This rather handsome, large land slug is a “leather leaf” slug in the family Veronicellidae — the mantle completely covers the body. However I don’t know enough to be able to tell you which genus or species it is. It may possibly be an introduced species in your area.

  • we found the exact same eggs but with a slug-like creature wrapped around it. It appears to be a slug, only it seems more like a leech. It was found in Houston, TX underneath a piece of lawn furniture in the dirt. It has eyes that come out like a slug, but the dorsal side seems drier than its underside.

  • The same slug is found in india. In satpuda mountains these are tremendous. These are also identified as Laevicaulis alte or spp. by ZSI of India, Kolkata. I am in confusion. This might be another species of Laevicaulis genus. Inform me your opinion.

  • I have these in my garden by the hoards. I’ll take a video if you like and post it if you would like?

  • Found exact same outside
    So they are in Australia too ?

  • Found exact same outside
    So they are in Australia too ?


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