Celery fly

The Celery fly (Euleia heraclei) is a species of tephritid or fruit flies in family Tephritidae.

Symptoms
A large blotch, yellow or brown, preceded by a short corridor that in the end mostly is completely overrun. Generally several larvae share a mine. Especially in fresh mines the green primary and secondary feeding lines are well visible. Pupation outside the mine.

Treatment
If the attack of celery fly is only light its possible to pick off the affected parts of the blistered leaves to remove the pest.

Chemical
A light spray with a greenfly bug spray or insecticide can also be used.

Prevention
When hardening off the plants, cover the boxes and seedlings with a fine net. Deep trenching in Winter will bury the celery fly pupae and prevent the fly from hatching out.