10 



plate Fig. ."), a^ d and c, as a rule the tissue is so tough that they 

 simply work over or along the outer surface, especially in turnips, 

 as shown in plate Fig. 4, c and d, and plate Fig. 5, b and c. How- 

 ever, the question in tliese crops is not ^\'hether the injury has been 

 sufficient to stop the development of the plant, but whether they are 

 injured at all, for as soon as the maggots have even worked into 

 the surface, as shown in the illustrations, the crops become largely 

 if not altogether unsalable. 



Tn the case of the cabbage it is a question as to whether the 

 ])lant can maintain enough roots to grow and develop a good head 

 in spite of the injury. As witli the radishes and turnips, the 

 nuiggots frequently destroy only the smaller roots or feed on the 

 surface of the tap root or both, as shown in plate Figs. 6 and 7, 

 but even this often results in a girdling. 8ometimes the maggots 

 get even into the center of the root, as is shown in plate Fig. 6, c, 

 which was taken from a field ]nitch ]ilant. The j^i'csence of the 

 maggot is indicated, especially when the plants are yoimg, by the 

 wilting and droo[)ing leaves, as shown in the illustration of the 

 field and experimental plots, ])late Fig:=;. t> and 10. If the injury 

 is not too severe the plant nuiy make an effort to recover and 

 send out a new supply of roots, as shown in ])late Fig. 7, h; but 

 unless remedial measures are resorted to as soon as the mag- 

 gots make their appearance, few of the attacked plants will re- 

 cover. In the plot just referred to, al)out sixty per cent, of the 

 plants had lieen destroyed. 



THE IMPORTED ONION MAGGOT. 



Pcffonnjid ccixtonim, Meade. 



This insect, as well as the fly into which it develops, ver^^ 

 closely resembles tlie species found upon the cabbage in appear- 

 ance, habits and develojunent. It also hibernates, as a rule, in 

 the adult stage, and with the warmer temperature of spring comes 

 from its winter quarters to deposit its eggs on such onion plants 

 as may be available. 



The fly, however, is somewhat larger than hrassicce, measuring 

 one-fourth of an inch in length, and is well shown in plate Fig. 

 1, a. As in the other species, the female may be distinguished by 

 the more widely separated eyes and the more pointed abdomen, 



