DISEASES AND ENEMIES 263 



they migrate in numbers for reasons not well under- 

 stood. 



The galleries of mole-crickets are easily located, the 

 raised and loosened soil denoting their presence. They 

 are situated just beneath the surface, and extend for 

 considerable distances. 



The food of the mole-cricket is principally vegetable. 

 They always attack succulent roots and stems, and 

 leave the hard, woody parts untouched. Vegetable 

 gardens often suffer greatly, and tomato, turnip, sweet 

 potato, melongene (aubergine), and cabbage are much 

 sought after, also tobacco, rice, and sugar-cane ; all of 

 these have much more to suffer from the mole-cricket 

 than cocoa. The attacks are especially destructive in 

 the dry season. 



The protection of crops against the mole-cricket is 

 not so difficult when the area planted is small, as is the 

 case with vegetable gardens. It is generally sufficient 

 to keep the place quite clear of weeds, to turn up the 

 soil in due time by hoe or spade, and to surround the 

 place by a deep trench. These same methods may 

 successfully be applied in the cocoa nurseries. After 

 the soil is turned up, the natural enemies of the mole- 

 cricket, e.g. fowls, will help to kill a great number of 

 the insects. Attempts have also been made to poison 

 the insects by means of poisoned horse-dung, 3 Ibs. of 

 arsenic acid to 100 Ibs. of horse-dung being applied to 

 one acre. 



These remedies are, however, too laborious for 

 application in the case of cocoa fields. Whenever the 

 appearance of mole-crickets is to be feared, the best 

 way is to raise the seedlings in well-protected nurseries, 

 and to plant them out when they are strong enough to 

 be no longer liable to the attacks of this insect. 



II. Borers. General Remarks. It has already 

 been stated that different species of borers are to be 

 found in most cocoa-growing countries. The life-history 

 of these different enemies varies in details, but in many 

 respects their mode of life is the same, and accordingly 



