The adult is a browish fly with a body length of about 2.5 mm. Scaptomyza flava larvae cause white 'corridor-blotch' mines when feeding between the upper and lower epidermes of the leaves of cruciferous plants of the Brassicaceae family.

Around the larval food plants such as fields of oilseed rape, cauliflower and cabbage.

In Britain mines are typically seen on the plant leaves in late spring and autumn.

Females are polygamous and mating begins soon after emergence. Female flies start puncturing leaves with their ovipositor about 4 hours after emerging and produce peak numbers of punctures within the first 12 hours of their adult lives and at this stage egg laying begins. This species has recently become a serious pest of brassica crops.

Widespread and fairly frequent in Britain, and now becoming increasingly common.

Thought to be fairly frequent in Leicestershire and Rutland.