912 EXPERIMENT STATION RECORD. 



wliicli are 2 tootlied ; and the cephalic spiracles have 12 divisions." The 

 pupa is shorter, measuring about 0.2 in. in length, and is of an elliptical 

 ovate form, and light brown, becoming darker with age. Specimens 

 are easily found in the soil about infested plants in June. 



Illustrations from micro-photographs of both sexes of the adults are 

 given. By a casual observer the adult fly might be mistaken for the 

 common house fly, which it resembles in general appearance, but from 

 which it differs by its smaller size, being only about 0.2 in. (5 mm.) in 

 length. The sexes differ considerably in aijpearance, as is shown by 

 the following descriptions: 



"The male fly is of a general dark ash-gray color, with 3 rather broad blackish 

 dorsal stripes on the thorax, and a wide, black, dorsal stripe extending along the 

 abdomen, becoming narrower toward its extremity and more or less dilated oppo- 

 site 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 snbcylindrical, narrow, and but slightly tapering. The eyes, occni)y- 

 iug a greater portion of the head, nearly touch each other above. The legs are 

 black and stroiiglj' bristled ; on the under side of each hind femur near its base is a 

 tuft of tliese bristles; which are characteristic of this calibage fly. This tuft 

 is quite noticeable on the femur of the male fly, especially when comparison is made 

 with the corresponding femur of the female; 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, uneiiual in size, on the inner side 

 of tlie hind tibia of the male insect that will help to distinguisli the species. 



" Tlie female fly is of a lighter ash-gray color, quite indistinctly striped on the 

 thoiax and abdomen, and not so strongly bristled as the male. Her eyes are also 

 quite widely separated above. The abdomen is of a more elongate ovate shape 

 with a pointed apex. There seems to be no special characteristic by which the 

 female fly can be I'ccognized and separated from some of the other common antho- 

 myiians; it is necessary that it be found associated with its male to determine it 

 with certainty." 



For comparison illustrated descriptions are given of the onion mag- 

 got [Phorbia ceparum)^ root maggot {Anthomyia radicum), and fringed 

 anthomyiian {Phorbia fusciceps). The onion maggot closely resembles 

 the cabbage root maggot in size, shape, and color, but differs in certain 

 anatomical features, especially in the arrangement and number of the 

 fleshy tubercles of the caudal segment. The adult onion fly resembles 

 the cabbage fly, but is slightly larger, and the hind femur is compara- 

 tively bare of hair at the base, while in the cabbage fly the base of the 

 femur carries a tuft of hair. The life histories are much the same. 

 But one specimen of the root maggot has been taken in the United 

 States, and therefore no immediate damage is anticipated from it. The 

 maggots of the fringed anthomyiian are much smaller than the onion 

 niaggitts or cabbage root maggots, and are not nearly so destructive 

 to vegetation. Tbey feed on a number of plants and also on the eggs 

 of the Kiicky Mountain locust. 



The relation of the cabbage root maggot to the club root of cabbages, 

 ■wliicli is i)t)pulaily supposed by gardeners to be caused by the insect, 

 is di-scussed, and the disease is shown to be due to the cabbage slime 



