I love the little designs I see in leaves made by “mining” insects. In the picture above, you can see trails from leaf miners on the leaves of columbine and on a species of lily. The lines are made by larvae of beetles, flies, or moths that live inside the leaf. They crawl around in between the upper and lower layers of the epidermis, munching on the mesophyll cells. Being sandwiched between the layers of the leaf epidermis, the larvae are safe from predators while they’re growing. As adults, they emerge from the leaves, and then the females will lay their own eggs on the surfaces of other leaves and the cycle will begin again.