Circular, lower-surface blotch [mine], about 5 mm in diam, often quite a number together on a leaf. Upper surface wart-like, strongly reddish discoloured, opaque. At the lower surface the mine is closed only by the epidermis. The larva is easily visible, as is its food: drops of liquid resulting from external digestion. Pupation sometimes in the mine, sometimes in the soil. At least two annual generations. Pupa in a white cocoon.. .

The biology of Cystiphora species forms a transition between the mining and galling ways of life.

On Sonchus oleraceus and S. arvensis.

Feeding of midges cause 3-5 mm galls dark red in color appears in rows all over the leaves. Number of gall may reach up to 50 for each leaf.

Sonchus (sow-thistle)

Leaf blister...Cystiphora sonchi (Bremi)

Galls are green or red, their upper surface convex, the lower surface flat. One larva occupies each gall...introduced into Canada from Europe...