Throughout the summer, two potted hazels have stood proudly in front of our bay window. Drawing back the curtains one morning, I immediately noticed that something didn’t look quite right – on some branches all of the leaf blades had been chewed down to their veins and midribs. When I went outside to investigate, I discovered hundreds of spotted regal sawfly (Nematus septentrionalis) larvae clinging to the foliage. At first glance, the 10mm-long green and black-spotted creatures could easily be misidentified as butterfly or moth caterpillars – but they had a clear distinguishing feature. In addition to their three pairs of forelegs, they sported six pairs of bright yellow prolegs, while Lepidoptera larvae have a maximum of five pairs.
While a few smaller individuals hid away on the underside of the leaves, most of the larvae were gripping the leaf edges and steadily munching their way inwards. They swayed hypnotically as they fed, a defence mechanism intended to confuse potential predators. When I extended a finger towards them, they reared up in unison, curling their bodies into an S shape in an attempt to repel me.
