THE DISEASES OF THE SUGAR-CANE. 301 



Fab. This form, or one closely allied to it, is met with wher- 

 ever the sugar cane is grown. It is not very easy to give 

 an idea of the injury caused by this caterpillar, which bores 

 its way in all directions in the juicy cane-stalks. In one 

 field, examined by the author in St. Kitts, five-sixths of the 

 crop was destroyed by the Diatraea/ whereas the total 

 destruction of crops is not unknown.'^ Its numbers may be 

 gauged from the following figures. On the Brangkal Estate 

 in Modjokerto in Java, 300,000 " borer " grubs were col- 

 lected from the canes in the space of four months ; and 

 this does not appear to have been an exceptionally severe 

 attack.^ 



The grub of a beetle, Sphenophorus obsairtis, originally 

 described as destroying the canes in the Sandwich Islands,* 

 has recently appeared in great force in Fiji. The whole 

 damage during 1892 was estimated at 16 per cent, of the 

 crop.^ 



Another beetle, Apogonia destructor., which commences 

 its flights during the West Monsoon,*^ does great damage 

 in Java to the roots of the cane plant. Great care is taken 

 in some estates to collect and destroy the mature beetles 

 before the laying of their eggs. In February, 1896, twenty- 

 three million were brought in by the collectors in ten 

 estates ; while in March of the same year, seventy-three 

 million were destroyed in twenty-one estates." 



The direct effect of these insect attacks is various. In 

 many instances the damage is temporary and the plant 

 survives. In others the vegetative apex or the roots are 

 destroyed and the shoot dries up. In the great majority 

 of cases, however, the injury is probably an indirect one. 

 The wounds made — especially by the stem-borers — serve 

 as a suitable nidus for semi-saprophytic on parasitic fungi 

 which are not able to penetrate the massive cuticle. 



7. This apparent liability of the sugar-cane to the 

 attacks of parasitic fungi and insects is not at all surprising. 

 Whenever plants are cultivated on a large scale, diseases., 



1 Barber (i), p. 79. - Cockerell (i). ^ Hein (i). 



^ Insect Life, i., 185, 1888. ^ Sugar Journal, -p- 183, 1895.. 



6 Zehntner (i). '^ Archie/, 1896, p. 465. 



