Pesticides, slug pellets and garden wildlife

Every spray, pellet and powder in the shed works by killing something. In a garden that is also trying to feed birds, hedgehogs and bees, that something is often their food, and sometimes them. This guide is about the link between garden chemicals and wildlife, in general terms. It is not a list of which products are legal. For that, we point you to the official sources.

The sources, opened on 14 November 2026, are the GOV.UK press release Outdoor use of metaldehyde to be banned to protect wildlife, published by Defra on 18 September 2020, Hedgehog Street’s garden hazards page, and Buglife’s bee hotel post.

How chemicals reach wildlife

There are two routes, and the second is easy to miss.

Directly. An animal eats a pellet, licks a treated surface or is sprayed. Hedgehog Street says slug pellets are the best-known chemical hazard to hedgehogs. It also warns that hedgehogs often lick freshly treated fences, so wood preservers can harm them, and suggests a water-based, environmentally friendly treatment instead.

Through their food. Hedgehog Street says herbicides can lead to fewer earthworms in lawns, and that insecticides can reduce the invertebrates hedgehogs rely on. The same is true for birds. Blue tits feed their chicks on caterpillars; robins, blackbirds and wrens hunt insects and worms. A garden that is sprayed clean of insects is a garden with less to feed a nest. That food-chain point is our general reading, and it is why this site’s planting and habitat guides keep coming back to insects.

Metaldehyde: what Defra announced

Metaldehyde is the active ingredient in the familiar small blue slug pellets. In the press release dated 18 September 2020, Defra said the outdoor use of metaldehyde was “set to be banned in Great Britain from the end of March 2022”, and that “Metaldehyde will be phased out by 31 March 2022.” The release said the decision followed advice from the Expert Committee on Pesticides and the Health and Safety Executive “about the risks that metaldehyde poses to birds and mammals”. It quoted the farming minister: “the risks metaldehyde poses to the environment and to wildlife are too great.”

That is what the 2020 announcement said. We have not opened the regulation itself or any later update, and the press release does not mention Northern Ireland. So this page does not tell you the current legal status of any product. If you have an old box of pellets in the shed, check the current guidance from the Health and Safety Executive or Defra on GOV.UK before doing anything with it, and follow your council’s advice on disposing of garden chemicals.

The same press release said pesticides containing ferric phosphate “can provide effective control”, and mentioned cultural methods such as planting slug-resistant varieties. That is the government’s description of alternatives, not a recommendation from us to use any pellet.

Slugs without pellets

Slugs are food. Thrushes, blackbirds, hedgehogs, frogs and toads all eat them. A garden that supports those animals has its own slug control, slowly. In general terms, gentler approaches include:

• Grow plants slugs leave alone, and protect only the few they love, such as young seedlings.
• Raise seedlings in pots until they are big enough to cope.
• Go out on a damp evening with a torch and move slugs off prized plants by hand.
• Water in the morning rather than the evening, so the surface is drier at night.
• Make the garden better for slug-eaters: a pond for frogs and toads, see ponds and amphibians, and gaps for hedgehogs.

These are common gardening practice rather than advice from the pages above.

Sprays and weedkillers

Our general advice is to use as few as possible, and none where you can avoid it:

• Accept some holes in leaves. Aphids on a rose are food for blue tits and ladybirds.
• Pull or hoe weeds rather than spraying them, and let some lawn weeds flower for bees.
• If you do use a product, follow the label exactly, do not spray open flowers, and keep it away from ponds and bird baths.

Buglife advises keeping the garden “chemical free” for pollinators; see bees and pollinator nests. The planting that replaces chemicals with a balance of predators and prey is in bird-friendly plants and berries and the wider approach in wildlife-friendly garden.

What this page does not cover

The full list of hazards for hedgehogs, including netting, pools and strimmers, is in hedgehog hazards in the garden. If you find a bird you think may have been poisoned, or several dead birds, do not guess. Read sick and dead birds for who to contact and what not to touch.

Are metaldehyde slug pellets still allowed?

Defra announced on 18 September 2020 that outdoor use would be banned in Great Britain from the end of March 2022. We have not checked the current regulation, so check HSE or Defra guidance on GOV.UK for the current position.

Are any slug pellets safe for hedgehogs and birds?

We do not say any pellet is safe. Defra’s 2020 release described ferric phosphate as an alternative, but Hedgehog Street lists slug pellets as the best-known chemical hazard to hedgehogs. Gentler, pellet-free methods are above.

Do weedkillers harm wildlife?

Hedgehog Street says herbicides can reduce earthworms in lawns, and insecticides the invertebrates hedgehogs eat. Use as little as possible.