Why Nettles?

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Everybody’s least favourite weed? Well yes – it stings, it gets everywhere and sprouts up all over. Even the flowers sting!

Yes, but. Anybody who is worried about biodiversity and loves butterflies will tell you that every garden should have a wild corner where nettles can thrive, along with the multitude of insects that are reliant on it for their survival. 107 different species have been recorded as associated with the plant, while 31 are restricted to it, meaning that they are more or less confined to stinging nettle and its close relatives for survival. These include beetles, flies, plant bugs and, of course, butterflies and moths. In fact, some of our favourite butterflies are entirely reliant on nettles as plant food for their caterpillars.

At the Calon y Fferi site, we’ve been recording sightings of butterflies for the past three years and all of the following nettle-feeding types have been recorded. It used to be quite rare to see the comma butterflies, but in recent decades they have made a come-back and can now be seen in many locations. Two of our largest butterflies, the peacock and red admiral are frequently sighted, though the red admiral is mostly an annual migrant, flying in summer all the way from Africa. It does have a brood here and it is believed that these fly back, leaving a few to hibernate. It may be that, as the climate continues to warm, they will become year-round residents. The other all-year resident is the familiar and exquisite small tortoiseshell. This species can be seen throughout the warmer months from spring (when it comes out of hibernation) through to autumn.

There are also at least six species of moth that are dependent and seventeen that share with other plants. We have yet to conduct a series of moth trapping events to ascertain how many we have on site, but observations of their caterpillars have so far included the leaf-rolling and wonderfully named mother-of-pearl. Hopefully we can arrange for surveys this year.

So, you can understand why we would want to conserve some wildlife refuge areas at Calon y Fferi that have stands of nettle. The funny thing is that it won’t grow just anywhere. It’s a plant that needs phosphate in the soil. Human habitation automatically changes the soil composition to what it needs. Ash from wood fires, compost heaps, animal pens and feeding places all make it possible for nettles to flourish. These areas can persist for centuries, sometimes long after humans have left.

Gardener, please make room for a nettle bed so we can have more butterflies.

March 2020