Spring is well underway and that means that the natural world is at its busiest, however not all of the emerging species are welcomed by the green fingered amongst us bracing for impact from undesirable invaders.  In an interesting move which is bound to split gardeners opinions the Royal Horticultural Society have recently taken the decision to no longer categorise species such as slugs, snails, caterpillars and greenfly as pests. They are now encouraging gardeners to try and live in harmony with these long vilified beasties due to the wider benefits they can bring to the ecosystem.

As someone who has lost plenty of healthy plants to hungry gastropods I was surprised to discover that of the 44 species of slug identified in the UK only 9 types are responsible for causing havoc amongst the hostas. Like so many maligned species slugs and snails really do serve a greater purpose than perhaps we give them credit for, they are a nutritious meal for some of our favourite birds, amphibians and mammals and by leaving them to thrive we increase the chances of attracting these species onto our plots. They are also essential to keeping our gardens healthy as munching through dead foliage is an important part of their diets. 

Traditionally one of the most common ways to slow the gastropod invasion has been to reach for the slug pellets but this method whilst swift and effective in the short term can have devastating consequences for other species as these toxic tabs don’t discriminate. The active poison in them is called metaldehyde and has been found to cause harm to other non-target species who can mistake them for food and ingest them directly or are indirectly poisoned by eating other animals already contaminated by them. In birds ingestion can lead to nerve damage and the deaths of some mammals both wild and domestic including hedgehogs and cats has been linked with their consumption.  There are other chemical free methods of fatal control like beer traps which are safer for other garden visitors but the RHS is encouraging us to abandon lethal approaches entirely. Instead they suggest alternative deterrents such as companion planting to encourage these garden guests to dine on a sacrificial species along with creating barriers to snacking such as mulching round vulnerable plants and copper taping pots.

As to other garden invaders, greenfly again provide an invaluable source of nutrition for a wide range of species including other mini beats such as ladybirds and earwigs, they are a favourite food for blue tits who also love to feast on caterpillars. Ants even milk greenfly for the sweet liquid they secrete demonstrating once again the complexities and nuances of our eco system where even the tiniest of species assists others to survive and thrive. 

That’s not to say that every garden visitor is welcome. A number of undesirable invasive species are causing concern to wildlife experts amongst them the American bullfrog. These first came to our shores as pets but some have since been released into the wild and their presence can have devastating consequences for native species due to a deadly disease they carry. 

Harlequin ladybirds are also causing problems, these yellow winged and black spotted insects are much larger and more aggressive than our native species, they are cannibalistic and have already been linked to the decline of seven native varieties of ladybird and are the fastest spreading invasive species on record in the UK.

Invasive mammals are also causing issues for gardeners, I have heard more than a few complaints of muntjac dear, formally natives of China and Taiwan, chomping through prize blooms.  

The gardens themselves are not immune to the impact of invasive species, again deer have caused our gardening team headaches and we have a thriving population of grey squirrels which delight some visitors and infuriate others. And then there is the issue of unwelcome flora of which by far the most troublesome is the Japanese knotweed. You can learn more about that particular issue in my earlier blog: https://www.southcliffgardens.co.uk/a-knotty-problem/

It seems that our relationship with our gardens and their ecologies will be a source of ongoing conversation and one that will also be shaped by changes to our understanding of the natural world and with the increased interest in self sufficiency, what we want our private plots to achieve.

Gemma Alexander – Community Engagement Officer


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