Maderibeyza, Wikimedia Commons
Limax flavus is a medium to large air-breathing, land slug that measures about 3 to 4 inches when the body is extended. This slug has a yellow body with grey mottling and pale blue tentacles, which help the snail be aware of its environment. This species is strongly associated with human habitation, and is usually found in damp areas such as cellars, kitchens, and gardens. Limax flavus is nocturnal in nature and thus it is often unnoticed and people are unaware of how (relatively) common the species is.
Limax flavus is mostly associated with houses and gardens and is known to venture indoors especially cellars and basements, after dark. Feeds voraciously on seedlings and vegetables so where it does occur on agriculture and horticulture lands it can do serious damage. Despite being from the British Isles, this slug has been a confirmed host for the Asiatic Angiostronglyus cantonensis nematode in the United States, which is known to cause eosinophilic meningitis in humans. Thus far, A. cantonensis is not widely spread in the United States, but when it was found in in 1988 in Norway Rat populations in New Orleans Limax flavus populations were positive too. Thankfully, researchers have continually surveyed in southern Louisiana and the parasite does not seem to be spreading. There have been zoonotic occurences of A.cantonensis in Florida and Alabama but not human cases, and those were not thought to be transmitted by the yellow garden slug. Limax flavus has also demonstrated the ability to transmit the Central American nematode Angiostrongylus costaricensis (causes abdominal issues in humans) throughout the parasite's native range. Even though neither of the Angiostrongylus parasites are established in Texas yet, Limax flavus is not only an economic and ecological threat but a parasitological threat as well.
Eggs are laid in clutches of varying sizes from 12 to 32 eggs and joined together by strands of mucous. Egg clutches of L. flavus were frequently partially buried and measure 6.3 by 4 mm, several clutches can be laid by a single female slug in one day. In some, the outer gelatinous layer was a little thicker at the apices of the egg, causing it to appear more elongate. Overall, adults can live from 7.5 to 12 months.
Not much is known as to how Limax flavus got introduced into the United States but it was surely accidental. Slugs are known to hitch rides from the Mediterranean on pallets of tile and marble. Others bury deep in the soil of plants shipped around the world. Still others find their way into cracks on shipping containers, in crevasses of military hardware and aquarium supplies and between layers of wood products. Also, since Limax flavus is known to feed on vegetables and plant seedlings it could’ve been introduced through the crop or ornamental plant trade.
Southern Europe but well established in England, Ireland and Wales
U.S. Habitat: Limax flavus feeds on decaying matter and mosses like lichen or vegetables; so it can be found in gardens or in basements and cellars.
U.S. Present: AL, AR, AZ, CA, HI, IL, IN, KY, LA, MD, ME, MO, NJ, NY, TX, WA and WI
Please remove any of these pests from your yard but use gloves when handling them! Also, besure to wash your hands off with hot water and soap afterwards. For a non-toxic solution you can submerge them in soapy water overnight (in a full, water-tight container) and dispose of them the next day. Shallow traps baited with beer or apple cider have shown to be effective, and the slugs can be disposed of in the morning. To discourage snails and slugs on potted plants you can place copper stripping around the base of the pots.
For these pests, development of chemicals and research for biological control has been done mostly outside of the USA, and limits the options. Natural enemies of terrestrial slugs are relatively few. Some birds, especially ducks, feed on slugs and sometimes moles and shrews. Few predacious insects attack slugs, but occasionally in beetle suborder Coleoptera, the larvae of Lampyridae (lightning bugs) and adult Carabidae (ground beetles). Some parasitic flies (family Sciomyzidae and Phoridae) a few fungi and many protozoa are known to affect slugs. Phasmarhabditis hermaphrodita, a slug-parasitic nematode, is used in Europe to control slugs but is not allowed in the USA. Other nematodes found in the USA have been investigated for slug control, but the results were not encouraging. As mentioned in other gastropod invasive species pages, commercially produced metaldehyde slug traps can be set up to reduce slug populations; but slug bait is very toxic to domestic animals.
Barker GM. (ed.) 2001. The Biology of Terrestrial Molluscs. CABI Publishing, Wallingford, UK. 558 pp.
Branson, B. A. 1962. The slugs (Gastropoda: Pulmonata) of Oklahoma and Kansas with new records. Transactions of the Kansas Academy of Science (1903), 110-119.
Campbell, B. G., & Little, M. D. 1988. The finding of Angiostrongylus cantonensis in rats in New Orleans. The American journal of tropical medicine and hygiene, 38(3), 568-573.
Grewal, P. S., Grewal, S. K., Tan, L., & Adams, B. J.(2003. Parasitism of molluscs by nematodes: types of associations and evolutionary trends. Journal of Nematology, 35(2), 146.
Henderson I, Triebskorn R. 2002. Chemical control of terrestrial gastropods. Pages 1-31 in Baker, G.M. (ed.) Molluscs as Crop Pests. CABI Publishing, Wallingford, UK.
Karlin, E. J., & Bacon, C. 1961. Courtship, mating, and egg-laying behavior in the Limacidae (Mollusca). Transactions of the American Microscopical Society, 80(4), 399-406.
Kerney M.P. and Cameron R.A.D. 1979. A field guide to the land snails of Britain and north-west Europe. Collins.
Rambo, P. R., Agostini, A. A., & Graeff-Teixeira, C. 1997. Abdominal angiostrongylosis in southern Brazil-Prevalence and parasitic burden in mollusk intermediate hosts from eighteen endemic foci. Memórias do Instituto Oswaldo Cruz, 92, 9-14.
Teem JL, Qvarnstrom Y, Bishop HS, da Silva AJ, Carter J. The occurence of the rat lungworm Angiostrongylus cantonensis (Chen 1935) in nonindigenous apple snails in the Gulf of Mexico region of the United States. Hawaii J Med Public Health. 2013;72(6 Suppl 2):11–14.
Teixeira, C. G., Thiengo, S. C., Thome, J. W., Medeiros, A. B., Camillo-Coura, L., & Agostini, A. A. 1993. On the diversity of mollusc intermediate hosts of Angiostrongylus costaricensis Morera & Céspedes, 1971 in southern Brazil. Memórias do Instituto Oswaldo Cruz, 88(3), 487-489.