342 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



giving it a roughened appearance on the under side. This is 

 followed by a curling of the edge and a final rolling up of the leaf, 

 the upper surface always being rolled in. As this progresses the 

 smaller veinlets grow still larger and more irregular, knotlike 

 swellings appear at frequent intervals, and in extreme cases 

 little nipple-like swellings appear, extending to a height of nearly 

 one-fourth of an inch. This will be noticed first on a medium- 

 sized leaf, gradually spreading to the younger ones, while at the 

 same +,5me the beet almost stops growing and a large number of 

 fibrous roots are sent out. . . . The beet often continues in this 

 way throughout the season; in bad cases it shrivels and dies, 

 while in a few instances there is a partial recovery and a new set 

 of leaves, though the sugar content remains very low." 



Control. Practical measures of control do not seem to have 

 been very thoroughly tested. With a better knowledge of the 

 hibernating habits of the species, it may be possible to reduce its 

 numbers at that time. After the hoppers have appeared in 

 numbers they must be dealt with promptly. " A thorough 

 spraying with kerosene emulsion at a strength of 1 part of the 

 stock solution to 5 parts of water, would destroy most of the 

 insects that it hit, and by using a drag in front of the nozzles to 

 turn the leaves over and cause the insects to jump, most of them 

 would be reached." This would probably need to be repeated 

 in about ten days. Hopperdozers have often been successfully 

 used for collecting various forms of leafhoppers. A modifica- 

 tion of the form used against grasshoppers (see page 108), with 

 a couple of wings extending out on either side of the row and 

 covered with a sticky substance such as " tanglefoot " or that 

 described on page 523, would undoubtedly prove effective in 

 collecting the adults, particularly before the females have laid 

 their eggs, when they are more readily caught. A " hopperette " 

 designed by Professor G. C. Davis for use against leafhoppers on 

 celery in Michigan, is shown in Fig. 245, and may be readily 

 attached to the frame of a wheel hoe. The string across the 

 notch at .4 strikes the plants and causes the hoppers to jump 

 at the right time. By adding high wide wings to either side of 



