Rare sighting in the region - purple and pink grasshoppers

I AM a great fan of sunny weather, so last summer was wonderful. One day in early June, I had been up since 5am emptying moth traps that had been operating overnight. By mid-morning all the moths had been counted, species recorded, photographs taken and the moths released in a bramble thicket to protect them from birds. I found a nice grassy slope overlooking the Trout Lake and laid back in the grass enjoying the feel of the strong sunshine on my face.

I must have nodded off, because when I came round I felt something tickling my arm. I glanced down at my forearm and there looking back at me was a bright Purple Grasshopper. I had recorded these before in 2011 in exactly the same spot.

I got onto my hands and knees very carefully and began to gently part the grasses to disturb any more grasshoppers. Indeed, there were dozens of grasshopper nymphs in this one area. All of them were nymphs of the Common Field Grasshopper, chorthippus brunneus. I estimated that 25 per cent to 30 per cent of the grasshopper nymphs were pink, or deep purple.

This pink colouration is caused by a genetic mutation called erythrism, which is similar to albinism, but rarer. The genetic mutation is little understood and is caused by a recessive gene. The mutation results in one of two things happening, or even a combination of the two. There is a reduction, or even absence, of the normal pigment and/or the excessive production of other pigments, in this case red, which results in pink and purple morphs. To see so many in the same area suggested that they had the same parents carrying the recessive gene.

Field Grasshoppers lay their eggs in dry soil in late summer and early autumn. The eggs begin to hatch in April the following year. When they hatch from the egg, they are tiny vermiform (wormlike) larvae, but on wriggling to the surface of the soil, quickly shed their skin, to become tiny versions of adult grasshoppers. They become larger every time they shed their skin. After four or five moults, their wings are fully formed and they become adults, ready to breed.

During 2018, I found many different colour combinations of the nymphs. As well as the pink and purple morphs, I found straw coloured nymphs with a bright yellow stripe along the back. I found rust coloured nymphs, with black stripes along the back. The adults are normally brown, or greenish.

Most of the colour combinations of the nymphs seem to disappear after the final moult. The exceptions to this are the ones that have erythrism. I have read that the pink and purple morphs are picked off by predators, but this didn't happen to my grasshoppers. In fact, in a hot, dry summer, being green is not the best camouflage. I found plenty of pink and purple adults right through into autumn.

Another thing I noticed was that all pink adult grasshoppers had white eyes.

Why this mutation should occur again in the same spot after seven years I know not.

Grasshoppers are not an endangered species, but they are less common than they used to be. They prefer a longish sward of fine grasses and these days most grassland is heavily grazed. Even nature reserves tend to think it is a good idea to graze areas to keep the grass short and get rid of brambles. Not for grasshoppers it isn’t.

Birds will eat grasshoppers, but to be honest, I have never seen birds feeding on them at Bellflask. Shrews are their real nemesis and we have all three species here, even the voracious Water Shrew.

It will be interesting to see when this genetic mutation shows its presence again.

I have come across erythrism once before in another species. About 15 years ago a lady who lived near the level crossing on the Wensleydale Railway at Leeming telephoned to inform me that she had a pink blackbird feeding on apples in her orchard. I knew this lady well and she would often ring me for advice on waifs and strays she had found. I told her to take more water with it!

She was insistent that this bird was the size and shape of a blackbird, but was distinctly pink.

With Dr John Mather, the former chair of the British Ornithologists Union Records Committee, I drove over to Leeming to see this bird. The lady led us through her house into the garden at the rear, and within minutes, there before our very eyes, was a female blackbird which was a distinct shade of pale pink.

It wasn’t just a few feathers; the whole bird was pink.

I have read about pink elephants and pink tigers, and once every seven years, I come across pink grasshoppers, but pink blackbirds – now we are getting into the realms of fantasy!