Traditional slug pellets, made using metaldehyde are now banned from manufacture in the UK and you’ll be committing a crime if you use any old ones in your garden after March 2022. Most of the slug pellets now for sale in the UK use iron or Ferric Phosphate as their active slug killing ingredient. They are often labelled as organic, but are they really wildlife friendly slug pellets, and safe to use around pets and children?
The battle with the slugs is well underway in our garden right now. they’ve already had a go at my spinach and I know they’re looking forward to getting their jaws around my baby cabbages. What to do? I’m a committed wildlife gardener; we welcome hedgehogs, birds, frogs and a whole host of insects and invertebrates into the garden. But even I find it quite hard to love a slug. Once I’d looked into how slug pellets actually work though, I was prepared to go with a more live and let live attitude, even to these slimy little creatures.
How Do Slug Pellets Work?
Slug Pellets work by enticing slugs to eat a substance that is poisonous to them so that they will die. Usually slowly.
There are two main poisons used in the slug pellets sold to gardeners.
Metaldehyde, now banned in slug pellets in the UK, causes the slugs to stop producing their natural mucus so they slowly die of dehydration.
Ferric Phosphate, now the most common active ingredient in slug pellets, kills the slugs by iron poisoning. Like many things, iron is very beneficial in the correct amounts but can be extremely toxic when ingested in excess.
Whilst there hasn’t been much research done into the symptoms slugs suffer through iron poisoning, we do know a fair bit about the symptoms suffered by humans. These include nausea, vomiting and diarrhoea. The eventual cause of death is liver failure. Slugs are built differently from humans, so symptoms and cause of death may well be different too, but it’s reasonable to assume that iron poisoning won’t be a pleasant end for a slug.
Ferric Phosphate on its own is also very slow-acting as a poison, and it doesn’t break down easily in the slugs digestive system. So many of the new Organic Ferric Phosphate slug killers on the market have a substance called EDTA added. This helps to make the Ferric Phosphate more soluble and fast acting, but has other implication which we’ll take a look at later.
Why Are Slug Pellets Bad For Wildlife?
Where do I start? Well, the slugs themselves might be a good place.
A Horrible Death For Slugs
The first thing to consider here, when we are thinking about whether slug pellets can be wildlife-friendly is that slugs are wildlife, and however much of a pest they may be to us gardeners nothing deserves a slow, painful death.
They’re Tasty – and Not Just For Slugs
Next, we need to think about how slugs and enticed to eat the slug pellets. This is done by making them smell good – to slugs and to other animals too.
Some efforts have been made to stop other creatures from eating slug pellets. They are often coloured blue, which makes them less attractive to birds. Many metaldehyde slug pellets also contain the chemical Bitrex. This gives the pellets a very bitter taste and makes them unappetising for many creatures.
Nonetheless, there is plenty of scientific and anecdotal evidence to show that hedgehogs, birds, dogs and other creatures do indeed eat slug pellets. This, in the case of metaldehyde pellets, has been shown to cause illness and even death in both wild animals and pets. So if you have any metaldehyde slug pellets left in your shed we suggest you dispose of them safely straight away.
Poisoning The Food Chain
Lots of things eat slugs. Before (or even after) a poisoned slug dies other creatures may eat it and take that poison into their own bodies.
- Slow Worms
- And many garden birds such as blackbirds, thrushes and robins.
Though there is much variance between species in terms of how many poisoned slugs a given creature would need to eat before it too died, there has been plenty of research to show damage that ingesting even small amounts of pesticide can do to our wildlife.
Slugs Are Part of Our Ecosystem – Our Wildlife Needs Them
They may not be attractive and they may be a pest in the veg patch or on your Hosta’s. but slugs are part of our ecosystem and they have an important role to play.
Firstly, as we’ve just seen they are an important food source for all sorts wildlife. Whilst eating a poisoned slug may be bad for our frogs, birds and hedgehogs, having no slugs at all to eat is equally damaging.
We know that hedgehogs and many of our bird species are in serious decline. One of the key reasons for this is lack of food. Killing slugs is adding to that problem.
Slugs also eat decaying vegetation (actually in preference to your young plants if they can get it), so they play an important role in composting and soil conditioning.
We don’t know what other important roles slugs may be playing in the world. And it’s precisely because we don’t know that we should be very cautious about killing them.
So Are Organic Slug Pellets Safe To Use?
We’ve just been through reasons why it’s probably not a great idea to be killing slugs at all: they are an important source of food for our wildlife and they play a vital role in soil health. But if you really can’t put up with slugs in your garden could organic slug pellets be the answer? Surely something used in organic gardening must be safe.
The jury is out on organic slug pellets and if we had to offer advice we would suggest you steer clear until more research has been done.
Organic slug killers use Ferric or Iron Phosphate as their active ingredient. This on its own is fairly safe, as it is a pretty insoluble substance and not easily absorbed by animals.
But this proved to be a problem. As the slugs weren’t able to easily absorb the iron they were dying slowly, or not at all. So a substance known as EDTA has been added to many Ferric Phosphate products to make it more soluble. This means it works better as a slug killer, but it’s not yet known whether the addition of EDTA also makes these pesticides more toxic to other creatures. Early research on earthworms looks worrying.
EDTA is not considered to be an “active ingredient” so you will not see it listed on the packaging of slug killing products.
How Can You Safely Control Slugs?
Hopefully we’ve convinced you that killing slugs with chemicals is not the way forward for wildlife friendly gardeners.
Fortunately, there are a host of other methods at your disposal for dealing with a slug problem.
1. The Beer Trap
We’d rather you didn’t kill slugs at all, but if you must there are surely worse ways to go than drowning in beer!
Take a large yoghurt pot, glass jar or pint glass and bury it in the soil, close to the plants you want to protect. Leave at least 2 inches of the container above the ground. This will allow slugs to get in but keep out beetles. Half fill with beer or a mixture and milk and water and the slugs and snails will happily dive in. Remove the dead slugs from your beer traps daily.
2. Slug Repellents
Whilst slug pellets and other poisons are a big problem for wildlife repellents are slightly less of an issue. These are not bait which the slugs are meant to eat, they are just substances intended to deter slugs and therefore much less dangerous to other wildlife.
Commercial plant based repellents made with yucca extract are reported to be effective.
Or you can make your own garlic spray, or plant garlic near to the crops you want to protect to keep the slugs at bay.
Slugs have squishy and sensitive undersides and there are lots of things that they would much prefer not to slither over – even with the promise of a tasty snack on the other side.
Copper – gives them a mild electric shock. so copper tape around your plant pots, or copper mesh on the soil around plants to create a physical barrier can be an effective deterrent.
Wood Ash, Lime, Human hair and a host of other substances are thought to interfere with slugs all-important mucus. So sprinkling these in areas you want to keep slug-free could be an option.
Rough Surfaces like coffee grounds, bark gravel or rough-sided planters are all uncomfortable for slugs to slither over. We surround young plants with a circle or horticultural grit. this works well at keeping the slugs off and helps keep moisture in the soil too.
Encouraging slug predators in your garden could be the best way of keeping your slug population under control. Make your garden hedgehog-friendly, put out food and water to attract garden birds and make a wildlife pond for frogs and toads.
A healthy range of predators will soon sort out any slug problem without the need for the use of harmful chemicals. You may even get to the point of feeling some slug love yourself – though I’m not there yet myself!
Thanks for reading! I wish we could have told you that there are wildlife friendly slug pellets out there to help save your salad crops. But at the moment it looks like they just don’t exist.
We hope you have enjoyed this article and found it useful. do you have questions or suggestions? Or slug control strategies that have worked for you. We would love to hear from you. Leave us a comment below.