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Controlling Slugs and Snails

Slugs and snails are without doubt the worst pest in the garden.

Many times seeds are sown and appear not to germinate when in fact they have been eaten by slugs overnight. Their appetite is voracious and their taste in plants extraordinarily varied but they all prefer succulent seedlings that are least able to resist the damage.

It has been estimated that slugs can consume twice their own body-weight every day. A slug weighing 0.1oz would, over a 20 week growing season, consume an incredible 1.75lbs of plants and vegetables - each! Since a cubic metre of your garden can contain 200 slugs, you can see they're a major problem.

Because slugs are nocturnal you may only notice one or two in the day. Come out just after dusk with a torch and you will be horrified to see how many there are happily eating your prize plants.

Can You Win Against Slugs?

Slugs - Click for Larger VersionHaving already said how many there are in the garden, I'm afraid you have another problem. Slugs are hermaphrodites having both male and female organs, so every individual can lay eggs. They lay about 300 each in batches ranging from 10 to 50 at a time. The eggs, which look like tapioca, hatch after ten days but can take up to 100 days in cold weather. So even if you kill every slug in your garden within a couple of weeks you will have them back. This is a war you can not win outright but you can keep the problem under control

Controlling Slugs & Snails

There are many ways to reduce the slug population and the damage they cause.

Hunting and Trapping Slugs

The best time to catch slugs and snails is around dusk when they come out to feed. Take a torch, those you wear on your head are really good as they leave your hands free and you will find them. You can drop them into a bucket of salty water, chop them in half or save them to feed to chickens. Don't be kind and move them elsewhere, they'll just come back.

Placing a hollow half grapefruit or large orange will provide a place for them to hide. Lift the cover and you will find the slugs. Beer or milk traps work well but you need to empty them quite frequently, which can be a smelly unpleasant job.

Barriers to Slugs and Snails

Putting a barrier around your plants will stop slugs getting to them, unless they are inside your barrier already, of course. Crushed eggshells, sharp grit work to some degree as they don't like the sharp edges. Slug Stoppa granules are pretty effective and copper rings or tape work fairly well.

The problem with barriers is that they can be expensive to maintain and just trap slugs already inside.

Encourage Slug Predators

You do have some allies in the battle. Many birds will eat slugs for you as will hedgehogs. Slugs make up a quarter of a frog’s diet, they’re also popular with newts and toads. A garden pond is the best way to keep these predators around. Carabid beetles (black beetles) love eating slugs and their eggs so a really useful creature.

Biological Control for Slugs

Nematodes are very effective but only for a six week period from application. You purchase a powder and water it on the ground as directed. The powder is actually thousands of microscopic worms that kill the slugs even underground. Unfortunately the level falls after six weeks or so to normal levels so a re-application is needed to keep the slugs down. Can be expensive.

Slug Pellets

Slug pellets are very effective and cheap if used correctly. They've had some bad press about causing harm to wildlife, pets and predators but the evidence is actually quite slim for this when they are used correctly.

Dangers of Metaldehyde Based Slug Pellets

Live slugs are a key dietary feature of many wild birds, such as blackbirds, thrushes, starlings, rooks, crows, ducks, geese and a variety of seagulls. There is concern that slugs killed by pellets will be harmful to these birds if consumed, but there is no evidence to support this.

Indeed, investigations by conservation bodies have failed to find any evidence of slug pellets causing death to garden birds. There is also evidence that birds do not, in fact, eat dead slugs anyway.

It is not entirely clear why some bird populations such as song thrushes are decreasing, but a variety of factors may be involved, including increasing predation by magpies, cats and grey squirrels and general loss of habitat.

Many other animals, such as frogs, toads and hedgehogs also feast on slugs. Research indicates that they rarely eat dead slugs but in any event, so called ‘metaldehyde-poisoned slugs’ have been shown not to be harmful if eaten. Tests have also shown that other beneficial organisms, such as carabid beetles, ants, spiders and earthworms will be unaffected by the use of slug pellets.

Metaldehyde breaks down into harmless components such as water and carbon dioxide in the environment and does not have a cumulative effect in the food chain.

Use Slug Pellets Correctly

Many people think that more is better with slug pellets but ideally, each pellet should be about 10-15cm apart. Never pile them as they will be less effective and more accessible to pets who could eat a large amount and be harmed. The pellets are colored blue which has been proven to discourage birds from eating them.

Conventional slug pellets contain metaldehyde as the active ingredient

Wildlife Safe Slug Pellets

If you are not fully convinced of the safety of metaldehyde based slug pellets and many people are not, then you can use pellets based on Ferrous Phosphate, also known as Ferramol, which are approved in organic systems and will only kill slugs and snails, and will not harm children, pets, birds, animals or wildlife etc. if used as directed.

The slugs and snails are attracted to the bait in the pellets which they then ingest and then crawl away to die, leaving no dead slugs or snails around and no unsightly slime. Any bait not eaten breaks down rapidly to iron and phosphate nutrients as part of garden soil.

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