458 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



that district normally has a heaw rainfall, it may have hindered the 

 reproduction of the parasites, just at the time that they were getting 

 started. This failure, however, led to the conclusion that, for some 

 unaccountable reason, the Tachinids could not be established in North 

 Queensland. Taking the above into consideration, I was particularly 

 gratified to find that the flies had not only maintained their existence 

 at Mossman, but had actually spread to even the most-distant portions 

 of the district. 



Previous to 1910 the beetle borer had become a serious pest at 

 Mossman, — a fact which probably led Muir to select this locality as a 

 station in his transfer of the parasites from New Guinea to Hawaii. 

 In his bulletin^ he states that before leaving Mossman it was found 

 that a few of the escaped flies had established themselves in cane near 

 the cages and were breeding quite freely. His work was carried on in 

 the Mill Nursery; and fortunately for the parasites, this cane was not 

 fired annually as is the custom with the ordinary field crops; hence 

 there was an abundance of borer grubs, and the flies had every 

 opportunity to multiply. Furthermore, seedcane was taken from this 

 nursery to various parts of the district, and this undoubtedly was an 

 important factor in the rapid distribution of the parasites. At any 

 rate, in one case I found them fully 15 miles distant from this center, 

 with long stretches of forest intervening. 



The borer beetle is no longer a serious pest in the Mossman district 

 — in fact it is thoroughly under control. In standing xsane, it is now a 

 difficult matter to locate a borer-grub that has escaped the vigilant 

 search of these friendly insects. During the collection of the parasites 

 for transfer to other infested districts, I estimated that fully 90 per cent 

 of the grubs were destroyed by the flies. It was only where the stalks 

 had fallen and were buried up by trash, that the grubs escaped. 



The fact that these parasites have done so well at Mossman, is cer- 

 tainly very encouraging for their introduction into other nearby in- 

 fested districts. This work I have undertaken as opportunity arose. 



At first I tried transporting the parasitized grubs in the canes to the 

 fields where I wished to establish the flies; but finding this a bulky pro- 

 cedure, I later collected only the grubs and puparia of the flies, which 

 I carried in jars. By this method the grubs do not injure one another 

 if a good quantity of frass is placed in the jars with them. I found 

 it better, however, to separate the puparia into another jar, as fast as 

 they emerged, to prevent the grubs destroying any that happened in 

 their way. 



By keeping the puparia covered with a plentiful supply of the frass 



1 H. S. P. A. Bui. 13, Ent. Ser. 



