492 BUI.I.KTIN 78. 



As the whole future destiny of the insect is enclosed in these 

 puparia, gardeners should be able to recognize the pest in this 

 stage so that they may destroy them at every opportunity, thus 

 ' ' nipping in the bud ' ' a future destructive crop of maggots. 



The adult insect. — After a certain period of incubation in the 

 puparia just described, this pest appears as a creature totally dif- 

 ferent from the familiar maggot. It is the adult insect, which is 

 known as the fly of the Cabbage Root Maggot by the few garden- 

 ers who are familiar with the pest in this stage. Both sexes of 

 the fly are shown greatly enlarged (the hair line beneath each in- 

 dicates their natural length) on plate I ; the right legs and wing 

 were removed before photographing so that the details on the 

 other legs and wing might not be obscured. By the casual 

 observer the adult insect might easily be mistaken for the common 

 house fly. It resembles the house fly in general appearance, but, 

 although it varies somewhat in size, it is considerably smaller. 

 Like the house fly, it has only two wings, but in the cabbage fly 

 these extend farther back beyond the end of the body and are shut 

 farther over each other on the back of the fly. The body of the 

 fly is about .2 of an inch (5 mm.) in length, and the sexes differ 

 considerably; some of these differences are well shown in the 

 figures on plate I, as will appear from the descriptions of each sex 

 which follow. 



The male fly is of a general dark ash-grey color with three rather broad 

 blackish dorsal stripes on the thorax, and a wide, black, dorsal stripe extend- 

 ing along the abdomen becoming narrower toward its extremity and more 

 or less dilated opposite the upper margin of each segment which is marked 

 with a narrower transverse black stripe. Many bristly hairs project from 

 different parts of the body, and the abdomen is sub-cylindrical, narrow, and 

 but slightly tapering. The eyes, occupying a greater portion of the head, 

 nearly touch each other above. The legs are black and strongly bristled ; 

 on the under side of each hind femur near its base is a tuft of these bristles 

 which are characteristic of this Cabbage-fly. This tuft is quite noticeable on 

 the femur of the male fly in figure 4, especially when comparison is made 

 with the corresponding femur of the female shown in figure 5 ; by this 

 character alone, the male insect can be recognized and separated from the 

 other common Anthomyiian pests. There is also a characteristic row of 

 short bristles, unequal in size, on the inner side of the hind tibia of the male 

 insect that will help to distinguish the species. 



The female fly, figure 5, plate I, is of a lighter ash-grey color, quite indis 

 tinctly striped on the thorax and abdomen, and not so strongly bristled a 



