146 



TUENIP AND CABBAGE -ROOT ATTACKS. 



gnawed out by the maggot lying in it. Or, in case we come to our 

 examination after the maggot has made its way out, still we have the 

 exit hole, the regularly eaten out cavity, and the dirt, or " frass" as it 

 is called, consequent on the feeding of the maggot, to prove exactly 

 what has been going on. There will very likely be decay also, for 

 injured Turnip and Cabbage-roots soon decay ; but this will be local at, 

 or starting from, the rotting remains of the galls, and very easily dis- 

 tinguishable from the masses of mere shapeless rottenness produced 

 by an old club.* 



Another of the insect attacks often prevalent to a serious extent, 

 and not always distinguishable from " Finger-and-Toe," is that of the 

 Turnip and Cabbage-root Flies. 



Anthomyia radicum. 



1, maggot of A. Irassicce; 2, 3, pupa-cases, nat. size and magnified; 4,5, A. radicum, 

 magnified, and lines showing nat. size. 



There are several kinds of these root flies, of which three species, 

 scientifically known respectively as the Anthomyia brassica, A. radicum, 

 and A. floralis, are so much alike in their various stages, and their 

 method of life, that it is difficult to distinguish them without very 

 minute examination. The figure of the kind more particularly known 

 as the Boot Fly, given at " 4 " above, conveys a good general idea of 

 the appearance of these flies when much magnified. The length and 

 extent of spread of the wings are given at " 5." The general colouring 

 is of black and grey, differently disposed in stripes, dots, &c., and there 

 is a little difference in size. The maggots are also very similar in 

 appearance, and are legless, cylindrical, and tapering to the head end, 

 which contains the hooks that serve as a feeding apparatus, and they 

 are blunt at the tail. When full-fed they turn (commonly in the 

 earth) to chrysalis condition in cases of about the shape and size 

 figured above of those of the Cabbage-root Fly ; these are of some 



* The methods of prevention are given further on, in order not to interrupt the 

 description of the appearance of the infestation. 



