COXTROL FOR WHITE GRUBS. 15 



17th July- 

 Pot No. 1 — No change. 



Pot No. 2 — One grub dead and black, one ahve. 

 Pot No. 3 — One grub dead from fungus, the other alive but 

 infected with black spot on thorax. 



21st July- 

 Pot No. 1 — No change. 

 Pot No. 2 — No change. 

 Pot No. 3 — No change. 

 31st July- 

 Pot No. 1 — Grub dead and black. 

 Pot No. 2 — No change. 

 Pot No. 3 — No change. 

 2nd August^ — 



Pot No. 2 — Grub dead from fungus. 

 Pot No. 3 — Grub dead from fungus. 

 Second Experiment. — On 10th July, 1920, thirty-five apparently 

 liealthy stage III. grubs of L. aJbohirtum were collected Avith a quantity 

 of soil at Greenhills and placed in a large pot. 



14th July — Examined these, and found eleven grubs dead and black 

 from the bacterial disease several being on the surface ; three more 

 were badly infected on the legs and around the thoracic spiracles ; also 

 two grubs had succumbed to the fungus. 



Kofe — This is 38 per cent, dead from the bacterial disease in three 

 ■days, under moist, cool conditions. 



17th July — Of the twenty-two grubs alive on the 14th, four had 

 succumbed to the bacteria and four to the fungus, leaving fourteen alive, 

 but two of these had bacterial infection on the front legs, one being 

 somewhat blackened on the body near the infected leg. 



21st July — Four more had died of the bacterial disease and six of the 

 fungus ; of the four remaining alive, two had bacterial infection on the 

 legs. 



31st July — The last grubs were dead, one from the bacterial diseaes 

 and three from the fungus. 



Third E.vjjerimerit.—Uth July, 1920, twenty-four pots were prepared 

 with soil from a Meringa field, where no disease organisms were known to 

 occur. Each pot was suppHed with a healthy stage III. grub of L. 

 ulbohirtum. Pots Nos. 1 to 18 were then infected by placing a grub 

 which had succumbed to the bacterial disease in each. Pots Nos. 19 

 to 24 were checks. 



17th July— All the pots were examined, but there was no change. 



22nd July In No. 10, the grub had the front and middle legs black 



•at the tip. No. 12, the grub had the left liind leg dead, the black starting 

 on the body. No. 13, the grub was dead, blackened around the spiracles. 



25th July— In No. 12 the grub was almost dead, the infection greatly 

 extended, the spiracles blackened. 



