Slugs and snails are the most common pests in British Gardens. Most slugs and snails feed at night, and the tell-tale slime trails, if present, will alert you to the level of activity. Damage is most severe during warm humid periods It’s pretty impossible to eradicate slugs and snails from your garden. Even if you were to lace the beds with toxic pellets and do nightly picking patrols, new creatures would quickly glide in from neighbouring properties .Slugs and snails do play a necessary role in the ecology of a garden. They break down decaying matter; disperse seeds and produce rich compost like waste. They are food for birds, frogs, toads, hedgehogs, ground beetles and ducks. Slugs and snails are hermaphrodites (they have both male and female reproductive organs). But they rarely fertilize themselves, and usually mates with another animal after an elaborate courtship.
They produce slime to assist mobility. Slugs remain active throughout the year, unlike snails, which are dormant during autumn and winter.
Slugs are soft-bodied molluscs which are the familiar slimy pests that cause havoc in the garden, eating and making holes in leaves, stems, flower buds, flowers, roots, corms, bulbs and tubers of many plants. There are about seven species of slugs that are garden pests. They can cause damage throughout the year on a wide range of plants, but seedlings and new growth on herbaceous plants in spring are most at risk! Each slug can eat twice its body weight daily and lay 500 eggs a year. That means a single slug can potentially have 250,000 grandchildren!. Most slugs live in or on the soil surface, but keeled slugs (Milax species) live and feed mostly in the root zone. Warmer weather, combined with damp conditions greatly increases their activity. Slugs are most active after dark or in wet weather. Reproduction occurs mainly in autumn and spring, when clusters of spherical, yellowish-white eggs can be found under logs, stones and pots .
There are 29 species of Snails in Britain, the fastest of which is the Speckled Garden Snail that can travel at 50 metres per hour. They are common and widespread in Britain and Europe. Although snails need moisture they can survive for long lengths of time in unfriendly hot and dry environments by going inside their shell and pulling down a thin white membrane like a shade. They can survive without moisture for at least 4 (four) years. Isn’t that depressing?
You may see the following symptoms:
They are herbivores and feed on decaying vegetation, algae, fungi, lichens and plant leaves. As a part of their herbivorous diet they often feed on garden plants and are therefore considered a big pest. Most snails have thousands of microscopic tooth-like structures located on a ribbon-like tongue called a radula which works like a file, ripping the food into small pieces.
- Slugs and snails sometimes leave behind slime trails, which can be seen as a silvery deposit on leaves and stems.
- They cause irregular holes in plant tissue made by their rasping mouth parts. They can kill young seedling by completely eating them.
- Black keeled slugs (Milax spp.) live underground and tunnel into potato tubers and bulbs.
Slugs and Snails are so abundant in gardens that some damage has to be tolerated. They cannot be eradicated so target control measures on protecting more vulnerable plants, such as hostas and young vegetable plants.
A biological control (‘Nemaslug’) specific to slugs, with no adverse effect on other types of animal, is available in the form of a microscopic nematode or eelworm that is watered into the soil. The nematodes (Phasmarhabditis hermaphrodita) enter slugs’ bodies and infect them with bacteria that cause a fatal disease.A moist soil and soil temperatures of 5-20ºC (41–68ºF) are required, therefore control is most effective during spring to early autumn.
Chemical control for Slugs and Snails.
Scatter metaldehyde slug pellets ( examples are Scotts Slug Clear Advanced Pellets, Bio Slug and Snail Killer Pellets, ) thinly around vulnerable plants, such as seedlings and young shoots on herbaceous plants. A liquid formulation of metaldehyde (Scotts Slug Clear) is available for watering on to ornamental plants and the soil.Pellets may harm other wildlife, pets and young children if eaten in quantity, although slug powders based on aluminium sulphate (such as Doff Slug Attack) are less toxic .A relatively new form of pelleted bait containing ferric phosphate (Growing Success Advanced Slug Killer and ‘Sluggo’ ) It causes the snails to stop feeding and die in several days is also relatively non-toxic to vertebrate animals. In addition what is left from the Sluggo is good for the soil Most plants, once established, will generally tolerate slug damage and control measures can be discontinued. Other non chemical controls
Preventive measures you can take include:
- Transplant sturdy plantlets grown on in pots, rather than young vulnerable seedlings. Protect transplants with plastic bottle cloches.
- Place traps, such as scooped out half orange, grapefruit or melon skins, laid cut side down, or jam jars part-filled with beer and sunk into the soil near vulnerable plants. Check and empty these regularly, preferably every morning. Proprietary traps are available from garden centres.
- Place barriers, such as copper tapes (Fito Slug Stoppa Tape, Agralan Copper Slug Tape, Growing Success Slug Barrier Tape) around pots or stand containers on matting impregnated with copper salts (Slug and Snail Shocka, Agralan Slug and Weed Mat). Moisture-absorbent minerals can be placed around plants to create slug barriers (New Horizon Natural Slug Barrier, Fito Slug Stoppa, Growing Success Slug Stop, Vitax Slug Off, Gem Slug n Snail Repellent). Gel repellents (Westland Slug Blocker Eco Barrier Gel, Greenfingers Slug Defence Gel) can also be used to create barriers around plants. All of these products are available from garden centres.
- Go out with a torch on mild evenings, especially when the weather is damp, and hand-pick slugs into a container. Take them to a field, hedgerow or patch of waste ground well away from gardens, or destroy them in hot water or a strong salt solution.
- Some birds, frogs, toads, hedgehogs, slow-worms and ground beetles eat slugs and these predators should be encouraged in gardens.
- Rake over the soil and remove fallen leaves during winter so birds can eat slug eggs that have been exposed.