INJURIOUS AND BENEFICIAL INSECTS OK CALIFORNIA. 



337 



The pointed end is dusky and there are two minute black spiracles on 

 the truncate end. The puparia arc regularly oval, distinctly segmented, 

 from light reddish-brown to dark brown in color and average ] inch 

 in length. 



Life History. — The winter is passed in the adult and pupal stages. 

 The hibernating adults and those transforming from the pupa? begin to 

 emerge in the spring and to lay eggs upon the host plants. They are 

 deposited singly or in small, loose masses upon the young leaves near 

 the crown of the host or upon the root, if it protrudes above the ground. 



Fig. 335. — Longitudinal sections of radishes, showing work, 

 maggots anil puparia of the Western radish maggot. Phorbia 

 planipalpis (Stein). Natural size. (Original) 



The young maggots, on hatching, burrow directly into the roots, com- 

 pletely ruining them for market purposes. The entrances to the bur- 

 rows soon become darkened and usually juices exude during the earlier 

 periods of their work. When full-grown the maggots pupate in the 

 burrows or in the soil near the roots. Rarely the pupae have been found 

 among the green leaves. The adults of the first or second brood begin 

 to issue in August and September, and the eggs for another brood are 

 laid immediately. On September 10th the writer was able to take all 

 stages of maggots, eggs, pupee and adults. There appears to be several 

 broods a year. 



Nature of Work.-The illustrations (Figs. 334, 335, 336) show well 

 the work of this fly. Burrows are made through portions of or the 

 entire roots, either killing the plants outright or making them unfit for 

 market purposes. 



22— 13GG4 



