DIPTERA. 415 



to have been obtained from the human body. It is not impossi- 

 ble that they may have, been swallowed with turnips, or other 

 vegetables, eaten when going to decay. 



Radishes,- while growing, are very apt to be attacked by mag- 

 gots, and rendered unfit to be eaten. These maggots are finally 

 transformed to small, ash-colored flies, with a silvery gray face, 

 copper-colored eyes, and a brown spot on the forehead of the fe- 

 males ; 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, to- 

 wards 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 yel- 

 low 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. West'wood with copies of two articles* by 

 him, on the onion-fly [Anthomyia Ceparum), which, in the mag- 

 got 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 maggots come to their growth in about two 

 weeks, turn to pups within the onions, and come out as flies a 



* See the " Magazine of Natural History," Vol. VH., p. 425, and the "Gar- 

 dener's Magazine," Vol. XIII,, p. 241. The same insect is also doicribcd and 

 figured in Kollar's " Treatise." p. 157. 



