by Jenny Dixon

Wharfedale Naturalists Society

wharfedale-nats.org.uk

AS a naturalist I try to appreciate all living things, but sometimes this isn’t easy. I have no trouble with the usual suspects: spiders – love them, rats and mice – no problem, snakes – beautiful and fascinating creatures. But – slugs? I really have to struggle against not just squeamishness, but also downright hostility. This, I realise, is not the antagonism of a keen gardener; snails (those rather jolly molluscs reminiscent of cheerful Brian in The Magic Roundabout) do far more damage to my runner beans. No – it’s the nasty habit of our garden slugs to trickle through impossible gaps in the backdoor at night and leave their sticky traces over the kitchen mats.

But enough of such irrational antagonism – let’s seriously consider the slug. It’s an amazingly successful organism. Molluscs, the phylum in which my night visitors fit, is second only to the arthropods in size; its members have been with us since the Cambrian Age, much longer than mere Mayfly humanoids. They’re the most numerous of marine creatures, and have been our main food source over millennia. The humble limpet, though unpalatable, has saved humankind from starvation not just in prehistory (think of those great shell middens) but over recent centuries too. Molluscs are a source of luxury: pearls and Tyrian purple dye.

And how diversified! My slugs are related to cephalopods like squid and the beautiful and sensitive cuttlefish which change colour not just for camouflage but emotionally too. Like slugs they can pour themselves into impossibly small spaces – but with such fluid grace that we gasp with wonder. Being soft-bodied (mainly comprising water) slugs are liable to dry out, so favour damp. Whereas snails hibernate in large clusters, slugs retire from adverse conditions by burrowing into the soil. They are hermaphrodite – having both male and female genitalia. So, when slugs mate, they hang twined together and fertilise each other’s eggs. The clutch is laid in the soil from whence the tiny new slugs emerge.

There are huge numbers of species of slugs and snails in the world, many still unknown to science, and only a few are found in English gardens. Many of these are useful recyclers, devouring decaying vegetative matter; only a few are serious pests on living plants. Relocating them is pointless: they have an excellent homing instinct. Pesticides are harmful to other wildlife such as hedgehogs and thrushes. The wildlife gardener can use nematodes – a naturally occurring slug parasite - or protect plants with copper tape or “shocka” mats, as well as the traditional spreading of ashes or coffee grounds.

So – slugs: successful, often beneficent and intelligent creatures, I salute you - while carefully spreading shocka mats across my backdoor threshold!