They feed on cells between the upper and lower epidermal layers.
Though it often stays in the epidermal layers, the mould does not appear to be tissue specific.
Finally, it leaves only upper and lower epidermal layers of the leaf.
Full-grown larvae make a case using epidermal layers by cutting the leaf.
"I do not believe you are required to penetrate the epidermal layer."
These rip and tear at the epidermal layers and a small pool of blood is formed.
Mines are always started at the upper epidermal layer.
Also, the epidermal layer of evergreen leaves is thicker and in certain species, even has a waxy content.
This is due to colour remaining in the outermost epidermal layers of skin at the start.
All the ossicles, including those projecting externally, are covered by the epidermal layer.