Slug - Human Relevance

Human Relevance

The great majority of slug species are harmless to humans and to their interests, but a small number of species are serious pests of agriculture and horticulture. They can destroy foliage faster than plants can grow, thus killing even fairly large plants. They also feed on fruits and vegetables prior to harvest, making holes in the crop, which can make individual items unsuitable to sell for aesthetic reasons, and which can make the crop more vulnerable to rot and disease.

As control measures, baits are the norm in both agriculture and the garden. In recent years, iron phosphate baits have emerged and are preferred over the toxic metaldehyde, especially because domestic or wild animals may be exposed to the bait. The environmentally safer iron phosphate has been shown to be at least as effective as poisonous baits. Methiocarb baits are no longer widely used.

Beneficial nematodes (Phasmarhabditis hermaphrodita) are a commercially available biological control method that are effective against a wide range of common slug species. The nematodes are applied in water and actively seek out slugs in the soil and infect them, leading to the death of the slug. This control method is suitable for use in organic growing systems.

Other slug control methods are generally ineffective, but can be somewhat useful in small gardens. These include beer traps, diatomaceous earth, crushed eggshells, coffee grounds, and copper.

It is of scientific interest that salt kills slugs by causing water to leave its body owing to osmosis (demonstration) but this is not used for agricultural control as soil salinity is detrimental to crops.

In a few rare cases, humans have contracted parasite-induced meningitis from eating raw slugs.

In rural southern Italy, the garden slug Arion hortensis was used to treat gastritis, stomach ulcers or peptic ulcers by swallowing it whole and alive. Given that it is now known that most peptic ulcers are caused by Helicobacter pylori, the merit of swallowing a live slug is questionable. A clear mucus produced by the slug is also used to treat various skin conditions including dermatitis, warts, inflammations, calluses, acne and wounds.