IG ^[OXTHLY NOTES OX GRUBS AXD OTHER CANE PESTS. 



"The male Avasps have a habit of congregating in numbers at sun- 

 down, particularly during wet Aveather, and pass the night resting side 

 by side on dead twigs, so that on certain spots one can easily collect 

 them bv handfulls." 



CANE GRUB INVESTIGATION, FEBRUARY, 1918. 



The majority of the grey-back beetles are now in their third stage, 

 the stage in which they do their greatest damage to the cane roots. 

 We found them abundantly, following the plough, both at Greenhills 

 and Meringa. The first specimens of this stage, for this season, were 

 collected 25th January. 



Field Experiments. 



The cane at Meringa, which was badly infested wdth frencJii grubs 

 early in the season, continues to improve. Since this field is near by, 

 we have been able to keep close observation upon the activities of the 

 grubs, and their effect upon the growth of the cane. 



During the past month some small animal — presumably a bandicoot 

 — has dug small holes near the roots of the infested stools. Investiga- 

 tion shows that these holes are confined to the diseased areas, for there 

 is no diggiiig at the roots of the healthy canes. Furthermore, it is now 

 almost impossible to find frenchi grubs under the stools w^iere this animal 

 has Avorked. 



We made attempts to catch the animal with various rat-traps, baited 

 with grubs, Avithout success. In cA^ery instance the bait Avas removed 

 from the trap Avithout springing it. 



Our 10-acre i)lots at IMeringa ai'e noAv all ploughed for the second 

 time, in preparation for early planting. The second crop of Mauritius 

 beans on part of this Avas very heavy, and Avent under Avell (25th Janu- 

 ary), so there Avill be plenty of humus in this area. Arsenic Avas applied 

 to the vegetation on several of these plots, previous to the first plough- 

 ing, in. September, and it Avas interesting, in foUoAving the plough this 

 second time, to observe that there Avas a noticeable decrease of the grubs 

 oil the jioisoned areas. 



Distribution of Grubs at Green Hills. 



The relation of feeding trees to distribution of grubs is aa'cII illus- 

 trated oil a large estate like Greenhills. The centre of the estate sutrers 

 little, if at all, from infestation, Avhilc the fields bordering the forest 

 or scrub are often almost a total loss. Tliese observations are further 

 borne out in folloAving the plough in various parts of the estate. Very 

 fcAV grubs are turned up in the central fields, Avhile they become exceed- 

 ingly imincroiis on the edges of the plantation. 



