224 VEGETABLE FOES AND DISEASES 



with black hairs. When at rest on the Celery or Parsnip 

 plants the wings are folded in an upright direction. 



The fly first appears in April, and the female, larger 

 than the male and furnished with an ovipositor, places 

 eggs singly upon the upper sides of the leaves or 

 leaflets of Celery and Parsnip plants. Each female 

 deposits many eggs, the larva or maggot hatching out 

 in about six days, and this at once enters the leaf 

 tissues and forms a mine within them. The maggots 

 or larvae are light green, legless, the dark line of the 

 alimentary canal being visible along the back. The body 

 is somewhat thick, pointed at the head and squared off 

 at the tail end, upon which there are black tubercles. 

 In about a fortnight the larva is full-fed, when it changes 

 to a pupa, either in the leaf or in the ground. The 

 pupa case is oval, of a light yellow colour, sometimes 

 brownish, barrel-shaped, wrinkled and about one-eighth 

 of an inch long. The fly comes from the pupa -case 

 in a few days. There are several broods in the course 

 of the summer, and the pupae of the late generations 

 remain in the earth and in pieces of leaf and stalk, 

 the flies emerging the following spring or summer. 



Great injury is frequently done by the larvas or 

 maggots of the Celery Fly to Celery and Parsnips. 

 They make mines or passages in the leaves, and feed 

 upon the soft juicy substance. The attacked leaf or 

 rather leaflet soon contracts, whitish patches appear, 

 at first small but quickly increasing in size, involving 

 a large portion of the leaflet, and in a short time it 

 shrivels up. As many or most of the leaflets are 



