

1917] CURRENT LITERATURE 85 



and a careful reading of the paper emphasizes this fact. Conclusions must 

 therefore be drawn with considerable care. — Charles A. Shull. 



Insects and plant diseases. — Although both botanists and entomologists 

 have realized for a long time that insects are carriers of organisms of plant 

 diseases, very little attention has been given to the study of the subject. 

 However, there is now a tendency to take up this line of investigation. Four 

 papers have come to the reviewer's desk recently. 



Rand* 



Smith 



both 



summer and the winter carrier of the Bacillus tracheiplilus which causes the 

 wilt of cucumbers and other cucurbits. 



In a later paper by Rand and Enlows,* the authors not only confirm the 

 conclusions given by Rand in the first paper, but also include the 12-spotted 

 cucumber beetle (D. duodecimpunctata) as an important summer carrier of this 

 organism. In experiments by the same authors, the squash bug (Anasa 

 tristis), the flea beetle (Crepidodera cucumeris), the melon aphis (Aphis gossypii), 



and the 12-spotted lady beetle (Epilachna borealis) did not transmit the 

 disease. 



Another paper by Hyslop 6 on Triphleps insidiosus and corn rots gives 

 conclusive evidence that this insect is the carrier of the fungi causing ear rots. 



In view of the fact that this insect has been considered beneficial since about 

 188 1, Hyslop's studies are of more than ordinary interest. 



A fourth paper by Stewart and Leonard 7 records their results with a 

 number of experiments and comes to the conclusion "that all of the sucking 

 bugs found in the nursery are of more or less importance in producing fire 

 blight infections and must be considered tout ensemble. The relative importance 

 of each species is difficult to determine. By virtue of their method of feeding 

 and prevalence during each season, certain species are undoubtedly more 

 destructive than others. On the other hand, under special conditions when 

 a certain species is found in large numbers it may become of considerable 

 importance. Usually the tarnished plant bug is more injurious than the leaf- 

 hopper from the fact that the greater percentage of leaf-hopper punctures 

 occur in the leaf tissue. ,, — Mel T. Cook. 



4 Rand, F. V., Dissemination of bacterial wilt of cucurbits. Jour. Agric. 

 Research 5:257-260. 1915. 



s Rand, F. V., and Exlows, Ella, M., Transmission and control of bacterial 

 wilts of cucurbits. Jour. Agric. Research 6:41 7~434- 1916. 



6 Hyslop, J. A., Triphleps insidiosus as the probable transmitter of corn ear rot 

 (Diplodia sp. Fusarium). Jour. Econ. Entomology g:435~437- I 9 l6 - 



'Stewart, V. B., and Leonard, M. D., Further studies on the r6le of insects 

 in the dissemination of fire blight bacteria. Phytopath. 6:152-158. 1916. 



