Leopard Slug

Limax maximus

Summary 4

Limax maximus (literally, "great slug"), known by the common names great grey slug and leopard slug, is a species of slug in the family Limacidae, the keeled slugs. It is among the largest keeled slugs, Limax cinereoniger being the largest.

Physical description 5

Spotted garden slugs can attain at least 6 inches in length. They vary in color from yellowish-gray to brown with black spots on the mantle near the head and black stripes extending along the rest of the body. The tail area is wrinkled. There is a pneumostome or breathing pore on the back part of the mantle that this slug uses to breathe.

Range length: 15.24 (high) cm.

Other Physical Features: bilateral symmetry

Sexual Dimorphism: sexes alike

Taxon biology 6

Limax maximus, known also as “the giant garden slug,” is an invasive, terrestrial member of the phylum Mollusca, class gastropoda (Gaitán-Espitia 2012). Some other common names include “tiger slug” and “great grey slug” (McDonnell et. al. 2009). Recognizable by its black spots and yellowish-gray body coloration, this slug can reach lengths of 100 mm or greater (Simpson 1901). This gastropod’s native geographic distribution is in Europe, North Africa, and Asia Minor (Western Palearctic) (Gaitán-Espitia 2012). These slugs are constricted to living in places where they can have easy access to water since they have poor ability to retain water and easily dry out during the day (Kaya and Mitani 2000). Therefore, this need for moisture is partially why this mollusk is nocturnal (Boycott 1934). It has been introduced as a troublesome pest to North America, New Zealand, South America, Australia, and some Pacific Islands (Gaitán-Espitia 2012). The amount of dampness in an area determines the time able to be spent breeding and feeding since water is necessary to form mucus for movement and eating (Boycott 1934). Also known as the “greenhouse slug,” this invader is a generalist that has wreaked havoc on horticultural plants worldwide (Kaya and Mitani 2000). This gastropod eats fresh and rotting plants, more specifically tubers, fruits, leaves, roots, bulb flowers, ornamental plants, and perennial herbs (Kozlowski 2012). Though these slugs are simultaneous hermaphrodites, they are unable to self-fertilize (Simpson 1901). Instead, a unique, complex, lengthy mating procession occurs in which male parts of two of these gastropods intertwine (Pilsbry 1948). These slugs tend to not be seen in groups (McDonnell et. al. 2009).

Boycott, A. E. 1934. The Habitats of Land Mollusca in Britain. Journal of Ecology 22:1–38.

Gaitán-Espitia, J. D., M. Franco, J. L. Bartheld, and R. F. Nespolo. 2012. Repeatability of energy metabolism and resistance todehydration in the invasive slug Limax maximus. Invertebrate Biology 131:11–18.

Kaya, H. K., and D. K. Mitani. 1999. Molluscicidal Nematodes for Biological Control of Pest Slugs. Pages 1–4. . Davis.

Kozłowski, J. 2012. The Significance of Alien and Invasive Slug Species for Plant Communities in Agrocenoses. Journal of Plant ProtectionResearch 52:67–77.

Mc Donnell, R. J., T. D. Timothy D. Paine, and M. J. Gormally. 2009. Slugs: A Guide to the Invasive and Native Fauna of California. Pages1–21. Oakland.

Pilsbry, H. A. 1948. Land Mollusca of North America: (north of Mexico). The Academy of Natural Sciences of Philadelphia 2:524–527.

Simpson, G. B. 1901. Anatomy and Physiology of Polygyra albolabris and Limax maximus and Embryology of Limax Maximus. Bulletin ofthe New York State Museum 8:244, 277–279, 290–294.

Distribution 7

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) This species is fairly cosmopolitan globally but probably has a European origin in Europe, North Africa, and Asia Minor. It has been introduced widely around the world including Asia Minor, Australia, Canada, Europe, Mexico, New Zealand, the United States (including Hawaii and Alaska), Africa, and South America.

Habitat 8

Habitat Type: Terrestrial

Comments: This species is common in gardens and buildings, and margins of native forests, but does not seem to penetrate far into undistrubed forests, although it can be abundant in modified forest remnants and secondary forests (Barker, 1999).

Ecology 9

The mating ritual involves two slugs climbing onto something high, usually a twig, then lowering themselves on a rope of slime. They then intertwine, in mid-air, and extrude their genitalia to exchange sperm.

Behaviour 10

L. maximus is an aggressive slug species both in the wild and the lab, especially in high densities, often killing and eating other slugs both of their own and other species (Rollo & Wellington 1979).

Defends itself through tail-wagging (and slapping) and quick fleeing (Rollo & Wellington 1979).

Homes to shelter (Cook 1979).

Engages in a conspicuous form of mating. A pair of L. maximus hangs from a long mucus thread, their bodies and blue-white penes encircle each other, and they exchange sperm on the ends of their penes (Quick 1960).

Development 11

Eggs are approximately 1/4 inch in diameter, and when first laid, they are colorless and transparent. Gradually, the eggs become cloudy, resembling small pearls. Development is direct whereby larval stages occur within the egg, and eventually, tiny slugs emerge from the eggs. Limax becomes sexually mature in two years.

Sources and Credits

  1. (c) Ondřej Zicha, some rights reserved (CC BY-NC), https://www.biolib.cz/IMG/GAL/165.jpg
  2. (c) Michal Maňas, some rights reserved (CC BY-SA), https://www.biolib.cz/IMG/GAL/1490.jpg
  3. (c) Kathleen, some rights reserved (CC BY-NC), http://www.inaturalist.org/photos/508774
  4. Adapted by Ken-ichi Ueda from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Limax_maximus
  5. Adapted by Ken-ichi Ueda from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/25065377
  6. Adapted by Ken-ichi Ueda from a work by (c) A. Linder, some rights reserved (CC BY), http://eol.org/data_objects/22982018
  7. Adapted by Ken-ichi Ueda from a work by (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28873102
  8. Adapted by Ken-ichi Ueda from a work by (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28873106
  9. Adapted by Ken-ichi Ueda from a work by (c) Unknown, some rights reserved (CC BY-NC), http://eol.org/data_objects/3043278
  10. Adapted by Ken-ichi Ueda from a work by (c) Paustian, Megan, some rights reserved (CC BY-NC), http://eol.org/data_objects/17765008
  11. Adapted by Ken-ichi Ueda from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/25065378

More Info

iNat Map

Establishment introduced
Slug or snail slug