382 CARNEGIE INSTITUTION OF WASHINGTON. 



to correspondents. Considerable time has been consumed in identify- 

 ing, recording, labeling, and preparing herbarium specimens and pho- 

 tographs from these sendings. 



One phase of the cactus work has recently developed which is of 

 great interest and may prove to be of much importance. It is well 

 known that certain species of Opuntia were introduced into Australia 

 some 3^ears ago and have since overrun thousands of acres of the best 

 wheat lands of that country. The local states have spent large sums 

 of money trying to eradicate this pest and two scientific commissions 

 have visited America seeking insect enemies, but without success. 

 A few years ago a midge was found in the cactus house of the New 

 York Botanical Garden which threatened to destroy the entire col- 

 lection of flat opuntias. It is now believed that this insect parasite 

 was brought from the island of Curacao in 1913, and the same insect was 

 recently found again on some plants sent from Venezuela, indicating 

 that the native home is Venezuela and the neighboring islands. Dr. 

 Britton has just received a letter from the entomologist employed by 

 this second Australian Commission, stating that the fly found in the 

 cactus house furnishes a most promising lead for the destruction of 

 cactus plants. A series of experiments is now being arranged in 

 southern Texas. If these parasites should destroy or even check the 

 growth of cacti in Australia it would be of great value to civilization 

 and in itself would justify a hundredfold the outlay which has been 

 made on the cactus project. 



