Leaf Miner

I found this pattern on a walnut leaf. I believe that is caused by a leaf miner.
Caloptilia roscipennella is a Walnut Leaf Miner.
The larvae feed on Juglans regia. They mine the leaves of their host plant. The mine consists of an epidermal corridor, which is either lower- or upper-surface. The corridor widens into a tentiform mine, usually close to the leaf margin. Older larvae leave the mine and live in a leaflet, rolled into a tube. Pupation under a silk membrane in a conical roll at the edge of a leaf.