TWO ONION MAGGOTS 



213 



INSECT PESTS OF SUGAR BEETS 



Flea Beetle (Disonycha xanthomelcena Dalm.). This is a 

 small black flea beetle which, with its larva, eats holes in the leaves 

 of beets. The adults hibernate, laying eggs on the crown of the 

 plant in the spring. Plants so affected may be dusted or sprayed 

 with arsenate of lead. 



INSECT PESTS OF THE ONION 



Onion Thrips. A very small insect belonging to the order 

 Thysanoptera (Thrips tabaci Lind.). 



Description. Adults and larvae eat the epidermis of onion 

 leaves, causing them to wilt, turn white, and die. 



FIG. 227. The onion maggot. 



FIG. 228. Tritoxa flexa. 



Control. Tobacco extracts afford the best spray for this pest. 

 Three-quarters of a pint of nicotine sulfate in one hundred gallons 

 of water, with four or five pounds of soap added, is recommended 

 by the Cornell Station. Three sprayings should be given at inter- 

 vals of four or five days. Weeds should not be allowed to grow 

 about the edges of the field. 



Two Onion Maggots. One of these maggots (Pegomyia cepa- 

 rum Bouche) (Fig. 227) is a common pest of the onion, causing the 

 leaves to yellow. As a result of its attack, the plant generally 

 dies. Tritoxa flexa (Fig. 228) gives rise to a maggot which may 

 also work in onions. 



Control. Old, infected fields should not be used for onions; 

 rotate the crop and thus avoid this enemy. The poison spray 



