FLEA-BEETLES 317 



leaves, but the punctures serve as points for infection by the 

 early potato blight fungus. The injury to the foliage also has 

 a direct influence on the size and quality of the tubers. Injury 

 by flea-beetles is most pronounced during dr}^ seasons when 

 the plants are least able to withstand the loss of their foliage. 

 Tomato plants are most subject to injury when first trans- 

 planted. 



Means of control. 



On potatoes flea-beetle injury is best held in check by keep- 

 ing the plants wtII covered with bordeaux mixture. Frequent 

 and thorough spraying with this material not only makes the 

 plants distasteful to the beetles but also protects them from 

 infection by the potato blight fungus. Experience has shown 

 that spraying with paris green or arsenate of lead, as for the 

 Colorado potato beetle, is of little or no value in destroying 

 the potato flea-beetle, because the latter either avoids the 

 poison or eats so little of it as to be unaffected. Where an 

 arsenical is used in bordeaux mixture for the control of the 

 Colorado potato beetle, it is quite probable that many of the 

 flea-beetles are also poisoned, but it is a question whether 

 enough of them are killed to make it worth while to add the 

 poison for flea-beetles alone. It has been suggested that 

 sweetening the poison might make it more attractive but 

 experiments on Long Island have shown that repeated appli- 

 cations of sweetened arsenate of lead in bordeaux mixture are 

 injurious to the potato plants. When potatoes are thoroughly 

 sprayed every ten to fourteen days with bordeaux mixture 

 for the control of potato blight, a practice now commonly 

 followed by commercial potato-growers, it is possible to raise 

 a good crop in spite of the flea-beetle. Tomato plants are 

 most seriously injured by flea-beetles soon after transplanting 

 and should be kept well sprayed with bordeaux mixture until 

 the danger is past. 



