WHOLE VOL. APPLIED ENTOMOLOGY HOWARD 389 



until June 30, 1929. His retirement from public service was marked 

 by a large gathering at the Department of Agriculture and Stock at 

 which addresses were made by the Under Secretary of Agriculture 

 and by others. An account of this meeting and Mr. Tryon's full bib- 

 liography will be found in the Queensland Agricultural Journal for 

 August I, 1929, beginning on page 176. 



The prickly-pear work has been continued on a large scale and with 

 very considerable success. The Prickly-Pear Commission is now 

 controlled by the Queensland Government, by the Commonwealth, 

 and by New South Wales. It has a Queensland staff and is indepen- 

 dent of the Commonwealth Department of Agriculture. Mr. Alan P. 

 Dodd,.a young Queenslander, is Entomologist, and there is a large 

 staff. Mr. Dodd was previously known for his excellent work on 

 certain parasitic insects, especially Proctotrypids. He visited the 

 United States in 1924 and spent .some time in Texas, and was ap- 

 pointed to his present post on his return to Australia. 



In October of 1929 there was published under the authority of the 

 Commonwealth Prickly-Pear Board a full and well illustrated bulle- 

 tin entitled " The Progress of Biological Control of Prickly Pear in 

 Australia," by Mr. Dodd. This bulletin gives a full account of the 

 investigations and brings the work down to date. Of the insects lib- 

 erated, a Lepidopteron known as Cactoblastis cactorwn seems to be 

 doing the most efficient work. This insect was brought over from the 

 Argentine Republic. More than 300,000,000 specimens of this 

 insect have been liberated since the beginning of 1926, and Mr. Dodd 

 predicts that, at the present rate of increase and with the existing 

 avenues of distribution, it should be prevalent in two or three years 

 wherever prickly-pear occurs in Australia. Two other insects have 

 proved very important, the one a mealy-bug known as Dactylopius 

 tomentosus and the other a true plant-bug known as Chelinidea tabti- 

 lata. These species are from the southwestern United States. The 

 Cactoblastis breeds rapidly — so much so, in fact, that the Prickly- 

 Pear Board has revised its predictions and anticipates rather speedy 

 success. The most extraordinary amount of destruction of the plants 

 between October, 1926, and May, 1928, is shown by actual compara- 

 tive photographs. 



The officers in charge are taking most extraordinary precaution 

 against introducing insects that might attack cultivated plants. Even 

 some very important enemies of Opuntias have been denied admis- 

 sion by the Board, since there seemed to be danger that they would 

 attack other plants. This was notably the case with a large Mexican 

 weevil, Cactophagiis spiuolac, and with a North American' moth, 

 Osamia clarefacta. 



