98 



Control. The scarabee is a difficult pest to control. 

 When the attack has once begun, there is no way of reach- 

 ing the insect with any insecticide. Care should be taken 

 to plant only strong, healthy slips, which are free from 

 scarabee, and the potatoes should be dug as soon as they 

 are ripe. Potato slips for planting may be produced in a 

 nursery established for the purpose. Small potato roots and 

 pickings are taken from a field after a crop is harvested, 

 and planted in some favourable location, away from potato 

 fields. The roots and pickings used for this purpose should 

 be carefully examined, and any that show signs of scarabee 

 attack should be rejected. If such a nursery is maintained 

 for only six or eight months, it is not likely to become 

 sufficiently infested for the vines to be attacked. As soon 

 as any attack of scarabee is noticed in the nursery it 

 should be abandoned and a new one established. 



the sweet potato WORM (Protoparce cmgidata, Fabr.). 



Lepidoptera. 



The leaves of the sweet potato are often eaten by a 

 large green caterpillar (Fig. 110) which sometimes occurs in 



Fig. no. 

 About natural size. 



Potato worm. 

 {Imperial Depi, Agric.) 



such enormous numbers as to eat all of them, leaving only 

 the bare vines in the field. This is the larva of the sweet 

 potato hawk moth. This caterpillar when full-grown 



Fig. in. Potato worm. 

 Pupa. About natural size. {Imperial Dept. Agric.) 



