CHAPTER Xill. 



PESTS OF VEGETABLE CROPS. 



IN this chapter the pests o£ all vegetable crops will not be treated in 

 detail ; some few pests that deserve individual mention will be grouped 

 tog-ether. In small areas of vegetable crops the pests of field crops also 

 occur ; radishes in a garden are damaged by the same pests as rape and 

 mustard in the field. Above all, numbers of occasional pests occur in small 

 areas of garden crops; leaf-eating caterpillars are numerous, plant lice 

 and mealy bugs abundant ; the brown ants eat the cauliflowers, cockchafer 

 grubs eat the roots of any plant, and so on. Such numbers of insects 

 attack a vegetable or market garden that they cannot be discussed in 

 detail here. 



Sweet Potato Weevil. 



A small weevil,! very narrow in outline, with a conspicuous straight 

 beak, coloured in red and blue, is found in 

 sweet potato tubers in the ground. All stages 

 may be seen in the tuber and the beetle is 

 qu.ite characteristic. 



This is almost the only known specific 

 pest of sweet potato in India, a cosmopolitan 

 pest found throughout the tropics. The 

 weevil lays eggs singly on the tubers, 

 hatching into a small white legless grub 

 which at once tunnels into the potato. The 

 grub eats its way in the potato, filling the 

 tunnels with excrement and setting up decom- 

 position. 



The pupa is found in the potato, in a small 

 cavity closed at each end with particles ; the 



imago when it emerges eats its way to the surface and escapes. 

 The whole life history occupies about 



one month ; the broods succeed one 



another quickly and the pest continues 



to increase so long as the weather is 



warm. The tubers are attacked in the 



field, the beetle laying eggs in the thick 



stems on the tubers. A badly infested 



plant becomes weak and stunted, the 



Fig. 185. 



The Sweet Potato Weevil. 



{Magnified four times.) 



{From Tryon.) 



Fig. 186. 



The Siveet Potato Weevil. 



{Magnified four times.) 



{From Tryon^ 



* 7« Cylas tureipennis. Eohm. (Curculionidse.) 



Mg 



