XL 



The chief dipterous insects which infest prickly-pear are certain gall 

 midges belonging to thg genera Itonida and Asphondylia. The former produces 

 galls under the areoles, and, under hot-house conditions at least, these not 

 infrequently become the seat of secondary infection which leads to the destruc- 

 tion of the attacked plant. The species of Asphondylia which infest Opuntias, 

 live during their larval stage within the fruit or the flower bud, and either 

 destroy the seeds or else cause a proliferation, so that there is produced an 

 " abnormal fruit " from which a joint or a flower bud arises. In either case 

 seminal increase is prevented or restricted, and thus these insects are capable 

 of acting as important agents in controUing the spread of various species of 

 prickly-pear. 



Notwithstanding the insect fauna of the Opuntias of the United States is 

 relatively large in the matter of distinct insects, it may be pointed out that 

 our knowledge concerning it — both that derived from the records of others 

 and from the Commission's own observations — ^relates only to a limited section 

 of the cactus area, and that, therefore, other more or less potent insect enemies 

 of this group of plants may await discovery. This may be more especially the 

 case with regard to the cactus regions outside its limit, e.g., Mexico, Central 

 America, and South America. Accordingly it is anticipated that additional 

 natural enemies of the class, some of them quite as injurious as any yet discovered, 

 may exist and be utilised. 



In view of what has been stated above, we recommend that, for the time 

 being, the following insects be introduced into Queensland : — Moneilema, spp. ; 

 Ccenopceus palmeri ; Oerstceckeria hubbardi ; Mditara, spp. ; Mimorista 

 flavidissimalis ; Chelinidea, spp. ; Narnia, spp. ; the wild cochineal insects ; 

 Itonida opuntice and Asphondylia opuntice, from the United States : Zophodia 

 cactorum and its ally, the "Mendoza moth borer," from the Argentine Republic; 



The Commission has already introduced into Queensland certain destruc- 

 tive wUd cochineal insects, from Ceylon and South Africa. These have become 

 established, and have maintained their character for destructiveness, at the 

 Prickly-Pear Experimental Station, Dulacca. They should exert a powerful 

 influence in controlling 0. monacantha. Zophodia, which is destructive to a 

 large number of prickly-pears, including several of the Queensland pest species, 

 was also brought to this State, but most of the larvae have died. 



The insects whose introducticin is recommended may prove more harmful 

 or less harmful to cacti in Australia than in their native home. Then, again, 

 they may not be able to adapt themselves to our climatic conditions. 



In their native country they are more or less controlled by predators 

 and parasites, and therefore cannot exercise their full influence. It is conse- 

 quently a m.atter of great importance that, before admission into Queensland, 

 parasites should have been eliminated. It was for this reason, amongst others, 

 that the Commission consulted Dr. L. O. Howard, the chief of the Bureau of 

 Entomology, Department of Agriculture, U.S.A., and one of his senior officers, 

 Mr. W. D. Hunter, who suggested that comparatively few individuals of each 

 species, free from any parasites likely to control their activity, should be 

 introduced to our country, and these subjected to careful attention. This, of 

 course, would necessitate the providing of a suitable insectary under the control 

 of an entomological stafi with experience in this kind of parasitological work, 

 as well as in the technical details involved in receiving, multiplying, and 

 distributing such insects. 



The question of collecting, breeding, eliminating parasites from and 

 transporting desired insects to Queensland from the United States was discussed 

 with Dr. Howard and Mr. Hunter. It was assumed that the Government of this 



