6 MONTHLY NOTES ON CxKUBS AND OTHER CANE PESTS. 



that they feed largely upon humus and decomposing soil substances, 

 it would appear to be simply a matter of properly supplying and poison- 

 ing these organic bodies in the soil preparatory to cane planting. For- 

 tunately, humus shows a marked affinity for arsenic, which has a de- 

 floculating action upon soil, making it more retentive to moisture. 

 Chemical tests of certain soils of Hawaii, which have been treated with 

 arsenic for the destruction of weeds for the past five years, show that 

 all of the poison has remained in the top 4 inches of soil, without 

 injuring in any way the roots of the growing crop. If we can make 

 use of arsenic as a weed-killer, and at the same time poison the food 

 supply of the grubs, it will certainly be a profitable procedure. 



Experiments are now being undertaken with 10 acres in one of the 

 worst grub areas on Meringa Farm, in order to test out the various 

 suggestions as outlined above. This land is divided up into fifteen 

 plots, from which we hope to get some conclusive results. 



It is rather early for us to make recommendations, but we should 

 certainly say 'conserve the humus and apply lime.' Later we may be 

 able to suggest the best method of poisoning the grubs. In the mean- 

 time make use of every known method of combating these terrible 

 pests. 



CANE GRUB INVESTIGATION, SEPTEMBER, 1917. 



Though this is the slack season in the activities of the grubs, we 

 have been very busy in framing up our lines for attack, when they do 

 become active again. The following list will not only serve to illustrate 

 the comprehensiveness of these lines, but it will also indicate clearly the 

 necessity for considerable additional assistance, if they are to be soon 

 carried out. This assistance will be referred to again later: — 



1. A study of the distribution of species with relation to soil, 



timber, cultural methods, &c. 



2. Mapping of infested and non-infested regions. 



3. Morphological study of reproductive organs of beetles, Avith 



relation to the period of ovipositing, and the number 

 of eggs produced. 



4. Morphological study of the fungous parasites. 



5. Breeding of the various local parasitic and predaceous in- 



sects in cages. 



6. Introduction and breeding of beetle parasites from other 



countries. 



7. Experimental methods for the rapid nuiltiplication and wide 



distribution of our fungous parasites. 



8. Introduction of bacterial and fungous enemies of the beetles 



from other countries. 

 1>. A I'ui'tlier study of various light-traps for the beetles. • 

 10. A I'urtlicr study of repellents. 



