December, '19] ILLING WORTH: REARING WHITE GRUB PARASITES 455 



this is done the land becomes immune. This fact is particularly 

 noticeable in the older districts, like the Herbert River and Goondi, 

 where all the land was once more or less infested. Now that the clear- 

 ing has been far extended, all of the older fields are immune; the only 

 infestation being on the lands laying near the feeding trees. Hence 

 we might justly conclude, that by concerted effort, many of the infested 

 lands could be freed of this pest forever. 



Conclusion 



As would appear from the above, the outlook is rather encouraging, 

 in spite of the fact that the investigation has been carried on under 

 many difficulties. It has been real pioneering. The spirit of unrest 

 makes it hard to get the backing that a problem of such magnitude 

 requires. 



Practical results can only come from extensive application in the 

 field. Alread}^ this is started in a small way, but it will take several 

 years of conscientious investigation to bring about conclusive results. 



A SUCCESSFUL METHOD OF BREEDING PARASITES OF 



WHITE GRUBS 



By J. F. Illingworth, Gordonvale, near Cairns, North Queensland 



Since Scarabaeid beetles are found probably more abundantly in 

 Australia than in any other part of the world, we naturally find their 

 parasites well developed. Among these parasites numerous wasps 

 have been recorded — about 50 species, according to Froggatt^ have been 

 described from Australia. I have come in contact with only three 

 of the principal ones, in my investigation of the several species of white 

 grubs that attack sugar cane in North Queensland. 



In order to know more definitely the habits of these friendly insects 

 and to try to learn something of the relation of their h^'perparasites, I 

 instigated breeding work in the laboratory in 1917, using our two most 

 abundant species (Canipsonieris tasinanien.sis and C. formosus). 



My assistant, Mr. K. Jarvis, carried out most of the work, since my 

 time was largely occupied in the field. At the time tluit the breeding 

 was started, in December, tiie wasps were very numerous, flying over 

 grub-infested lands neai' our Station. I'rom these I collected several 

 females, and found tlieni \'er>- amenable to handling in small cages. 

 When placed in covered tins, holding about half-a-pint of soil, they 

 "dug theni.selves in" at once. Our usual i)ractice was to place a grub 

 in each of these tins, removing it whenever an egg was found attached 



' Australian Insects. 



