S4 SOME SOUTH INDIAN INSECTS, ETC [CHAP. XI. 



[*he propei rotation of crops is a matter of the utmost import- 

 ance from the purely agricultural point of view, quite apart from 

 the question of the control of crop-pests, yet at the same time it is 

 an obvious and practicable means to the latter end also. Not only 

 i- it had agriculture as a general rule to grow the same crop 

 continuously in the same soil hut. as pointed out above, such a 

 practice is of direct assistance to the spread and increase of crop- 

 ped. This again is a matter for co-operation between cultivators 

 ol adjacent lands as it is obviously of little use for one cultivator 

 to rotate his crops if his new crop follows a similar one of his 

 neighbour's and attracts all the pests which have lived in the latter. 

 So far as pests are concerned also it is the rule, not only that the 

 same crop should not he grown continuously, hut that naturally 

 allied crops should not he so grown. The potato and tobacco plants, 



lor example, are closely allied to one another, both belongir 

 the same Natural Order so that pests which attack the one are 

 ecially likely to find suitable food in the other; ginger and 

 turmeric, cotton and gogu mav also he cited, all the known pests 

 of the one readily attacking the other of each pair. For this 

 on trap-crops have been recommended, the principle being 

 that a small crop is grown before the main crop of tin- same or an 

 allied plant in order to attract all the insect-pests into the advance 

 or trap-crop which is then destroyed before the main crop is 

 iilticiently grown to he attacked by insects. This is all very well 

 in theory and in practice also on experimental farms and similar 

 place- where the trap-crop can be grown under strict and in- 

 telligent supervision and where it may be destroyed in due time 

 absolutely without fail. Hut unfortunately this is not the case with 

 the great generality of cultivators and great caution should 

 therefore he shown in recommending the growing oi trap-crops 

 on any general scale, for as a rule the simple-minded son () ( the 

 -oil cannol see the necessity for destroying the trap-crop at the 

 proper tune and does not do so; with the result that, instead of 

 checking his pests, he simply provides them with food and helps 

 them to thle oxer the period of normal scarcity before the main 

 ( top l- ready lor attack by them. 



The growing of mixed crops is a common practice in many 

 districts ; in the western taluqs of Bellary. for example, live or sj\ 

 different Crops (cereals, pulses, etc.) may often be seen growing 

 intersown in the same field. In such cases the cultivator seems to 

 distrust placing all his eggs in one basket, hi- idea being that, if one 

 or two crops fail, he will at least secure a harvest from the others. 



•A list of natura 11 \ allied plants is given on pag 



