134 



THE BOOK OF GARDENING. 



be taken in hand directly it is obsen-ed, as it spreads ver\- 

 rapidly, and is fatal to the rosarian's chances of success. 



Rose Galls. — The presence of these excrescences, often of 

 large size, upon Rose-trees both wild and cultivated, is usually 

 pazzling to the gardener. The most conspicuous is the Rose 

 Bede guar (Fig. 65), a leaf-gall of large size, and conspicuous 

 by reason of the long red or green hairs. It is due to the 



Fig. 65. — Stages in the Life-History of the Bedeguar Gaxe. 



punctures of one of the Gall-flies {Rhodiies rosce), a 

 puzzling lot of extremely minute insects. These creatures 

 puncture the parts in the process of egg-laying, and the 

 movements of the larvfe, combined with the exudations, affect 

 the tissues of growing cells which are capable of further 

 division. This is the theory of the late Professor Riley, 

 who paid considerable attention to this most intricate but 

 interesting subiect. In the illustration (Fig. 65), i is the Bedeguar 



