December, '19] illingworth: sugar cane borer parasite 459 



it was easy to maintain correct moisture and air conditions, until the 

 flies emerged, when they were placed directly in fields of borer-infested 

 cane. 



I have advised leaving the trash on the fields where I hberated the 

 parasites, for at least one season, since the usual practice of burning 

 when the crop is cut, though beneficial in destroying borers, is prob- 

 ably a rather serious set-back to the flies, until they are well estabhshed. 

 Once they get a foothold, however, burning does not do them serious 

 injury, and it is the best means we know of checking the borers. As a 

 matter in point, all of the cane land in the Mossman district is burned 

 over at the time that the crop is harvested, and still the flies maintain 

 themselves well. 



Natural Enemies of the Parasites 



As I found in Fiji, the ants {Pheidole megacephala) are omnipresent 

 in the cane fields of North Queensland. They often make their homes 

 in the borer-runs, after clearing out the accumulated frass. Naturally 

 predaceous, they are always ready for the flies as they emerge; and if 

 they get them before their wings are expanded, the flies fall an easy 

 prey. I have even observed the attack of the ants upon the mature 

 insect, which is quickly overcome if they succeed in attaching them- 

 selves to the legs; the fly is then dismembered and carried away. It 

 is only the perfectly healthy parasites that are able to escape, by 

 eternal vigilance. 



Fortunately, jumping spiders are not abundant in cane here, for 

 they are a mortal enemy of the flies during the whole of their adult 

 existence. 



Swallows, and other insectivorous birds, are rather numerous in the 

 fields, but I am not of the opinion that they act as a serious check 

 upon parasites of this character, since the flies tend to spend their time 

 down among the stalks of the cane plants, in their search for the borer 

 grubs. 



lilULlOCRAPHY 



1909. Miiir, Haw. IMaiit. Rec. I, p. 4U. 



1909. Muir, Haw. Plant. Rec. I, p. 25G. 



1910. Muir, Haw. Plant. Rec III, p. 186. 



1911. Villencuvo, Wicn. Ent. Zeit. XXX, p. 81. 



1911. Swczey, Haw. Plant. Rec. V, p. 131. 



1912. Swczcy, Haw. Plant. Rer. VII, p. 34r,. 

 1914. IllinKworth, .lour. Econ. Ent. VII, j). 390. 

 1914. Swrzcy, .lour. Econ. Ent. VII, p. 4.")."). 



lOK). Muir & Swezey, H. S. P. .\. Mui. Mil. Knt. Scr. 



