THE ONION-FLY. 617 



maggots, and rendered unfit to be eaten. These maggots 

 are finally transformed to small, asli-colored Hies, with a 

 silvery-gray face, copper-colored eyes, and a brown spot on 

 the forehead of the females ; they have some faint brownish 

 lines on the thorax, and a longitudinal black line on the 

 hind body, crossed by narrower black lines on the edges 

 of the rings. They vary in size, but usually measure rather 

 more than one fifth of an inch in length. They finish their 

 transformations, and appear above ground, towards the end 

 of June. The radish-fly is called Anthomyia Raphani, in 

 my Catalogue, from the botanical name of the radish, on 

 the root of which its larvae feed. It closely resembles the 

 root-fly (Anthomyia radicum) of Europe. 



Onions, soon after they come up in the spring, and until 

 they are grown to a considerable size, are often observed to 

 turn yellow and die. Many years ago I remember to have 

 seen them extensively affected in this way, so that there was 

 a failure of three fourths of the plants in a large bed. The 

 cause of their death was not suspected at the time, and no 

 examination was made for the discovery of insects in them. 

 Since then, I have been favored by Mr. Westwood with 

 copies of two articles* by him, on the onion-fly (Anthomyia 

 Ceparum), (Fig. 272, pupa and imago,) 

 which, in the maggot state, lives in the roots 

 of onion-plants in Europe, and causes them to 

 wither and perish exactly in the same way as 

 young onions do here. Hence there is good 

 reason to believe that the failure of our onion crop is caused 

 by the ravages of maggots similar to those of the European 

 onion-fly. The latter lays its eggs on the leaves of the 

 onion, close to the earth, so that the maggots, when hatched, 

 readily make their way to the heart of the onion. The 

 mascrots come to their growth in about two weeks, turn to 



* See the Magazine of Natural History, Vol. VII. p. 425, ami the Gardener's 

 Magazine, Vol. XIII. p. 241. The same insect is also described and figured in 

 Hollar's Treatise, p. 157. 



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