The Carrot Fly is a pest of Carrots, Parsley, Celery, Celeriac and Parsnip. It's the larvae which are most damaging to plants. They bore into the plant taproots, eating the inner contents, and disrupting the movement of water and nutrients.
Carrot Fly will deplete most of the rooting system of a plant, resulting in a substantial reduction in the top growth of the plant, which ultimately loses colour and wilts. Infested plants may also be susceptible to secondary rots.
The top growth of Carrots, Parsley, Celery, Celeriac and Parsnip should be monitored between mid-spring to late autumn when Psila rosae activity is highest.