Larva of Nepticula durella, commonly known as a bramble leaf-miner. In modern scientific classification, it is more widely known by the synonym Stigmella aurella - stock illustration

Lifestyle: As a "leaf-miner," the larva lives and feeds entirely within the tissue of a leaf, protected between the upper and lower surfaces.Host Plant: Its primary food source is the Bramble (Rubus fruticosus), though it can also be found on other plants in the Rose family, such as wild strawberry and agrimony.Diagnostic Mines: You can often spot their presence by the distinctive, winding "galleries" or tunnels they leave in blackberry leaves. These trails start very thin where the egg was laid and gradually widen as the larva grows.Appearance: The larva itself is typically amber-yellow with a yellowish-brown head. As seen in your magnified illustration, it has a segmented body characteristic of moth caterpillars.