228 VEGETABLE FOES AND DISEASES 



plants finely crushed nitrate of soda, mixed with a 

 little agricultural salt, will be advantageously applied 

 alongside of the plants in the trenches, not scattering 

 on the foliage, but on both sides clear of the plants, 

 about an ounce of the mixture per yard run of row, 

 repeating at intervals of a fortnight or three weeks. 



THE ILLUSTRATIONS REPRESENT CELERY AND PARSNIP FLY. 



A, fly : a y natural size : ^, enlarged three diameters. B, larva com- 

 monly called maggot : c, natural size ; d y magnified three times. 

 C, pupa or pupa-case : e, natural size ; f 9 enlarged three diam- 

 eters. D, attack of Celery Fly on Celery : g, blisters or whitish 

 blotches on leaflets in early stage of attack ; h 9 more advanced 

 stage of devastation ; /, leaflets destroyed by Celery Fly larvae. 

 E, leaflet of Celery showing : j 9 blister caused by Celery Fly 

 larva eating inner portion of leaf ; k, dirt or excrementitious 

 matter of maggot ; /, larva or maggot. F, leaflet of Celery 

 showing : m, blister ; , dirt of maggot ; o 9 pupa, sometimes 

 present in blister. 



ONION FLY (Anthomyia ceparum Syn. Phorbia 

 cepe forum). 



The Onion Fly is not unlike the common house fly 

 in general appearance. It is of a blackish colour, thickly 

 powdered with grey ; the sides of the thorax are pale, 

 and there are three dark lines on the back. In certain 

 lights the abdomen has a whitish lustre, with, in the male, 

 a darker medium stripe. The eyes are separated in the 

 male by a slender, black, white-bordered line ; the face 

 has a pale lustre and the forehead is black, as are the 

 antennae and palpi ; the legs are pitch black, the wings 



