13 



snpposerl that were a plantation formed entirely of one of these 

 more inmiune varieties it would necessarily escape with little or 

 no damage. The mere fact that the leaf-hopper will attack gram- 

 inaceous plants other than cane (in the absence of the latter) is 

 sufficient proof that such is not likely to be the case, for there 

 are naturally much greater differences between these and cane 

 than between the most different varieties of the cane itself. Rel- 

 ative immunity from attack is a most difficult matter to judge 

 of, because one can never be sure how much immunity is due to 

 the nature of the variety of cane and how much to other causes. 

 Even in a field of cane of one variety and apparently similar in 

 growth, one can frequently see the capriciousness of the leaf- 

 hopper in its attacks (a capriciousness notorious too' in other in- 

 sects) from the fact that certain spots are more badly attacked 

 than others. In some cases this is no doubt due to^ causes that 

 can be perceived by man, such as greater shelter from prevalent 

 winds, a ranker growth of leaf, presumably affording more abund- 

 ant juice for food, but in other cases no adequate cause for this 

 capriciousness is apparent. 



It seems certain that some varieties of cane will stand the 

 attack of leaf-hopper better than others. Mr. Eckart, Director of 

 the Hawaiian Sugar Planters' Experiment Station, has furnished 

 me with a list of new varieties of cane (see Appendix, Note II 

 below), grown there, arranged in order, according to the relative 

 injury that each sustained from leaf-hopper. 



There may come, however, so severe an attack that no cane can 

 resist it Thus we have seen plants of "Yellow Caledonia"' (at 

 the extreme end of the list) which were of the strongest and most 

 thrifty nature previous to the attack, some entirely destroyed and 

 others very badly injured after a bad outbreak. It is, however, 

 probable that from an attack of hopper which would entirely de- 

 stroy a field of ''Rose Bamboo," for instance, a field of "Yellow 

 Caledonia" might recover. 



