44 SOME INSECTS INJURIOUS TO TRUCK CROPS. 



and consisting of a dozen or more leaves. Over another beet of the 

 same size a check cage was placed. Seventeen days later the eggs 

 had just begun to hatch, and already the beet in the cage without any 

 hoppers was nearly twice the size of the first one. The' beet on which 

 were the leafhoppers continued to grow for a week or more, then 

 practically stood still, and on the seventeenth day it was apparently 

 smaller than when examined five days before. Seven days later a 

 large number of nymphs had hatched out, the outer leaves were dead, 

 and the rest looking sickly; ten days later than this the cage was 

 examined again and the beet was dead and dry, while the beet in the 

 check cage had again doubled in size. Twelve leafhoppers and their 

 eggs stoj^ped the growth of a beet in less than two weeks, and they, 

 together with their progeny, killed it in less than two weeks more. 

 The same number of adult specimens of Agallia, Nysius, or Empoasca 

 would scarcely have made an imiDression on a beet of that size. 



CHARACTERISTICS OF " CURLY-LEAF." 



The first symptom of '' curly-leaf " or '" blight '' of the beet is a 

 thickening of all the smaller veinlets of the leaf, giving it a rough- 

 ened appearance on the underside. This is followed by a curling of 

 the edge (PL III, fig. 1) and a final rolling up of the leaf (PL I, fig. 



I, j; PL II, figs. 2, 3; PL III, fig. 2), the upper surface always being 

 rolled in. As this progresses the small veinlets grow still larger and 

 more irregular, knotlike swellings appear at frequent intervals (PL 

 III, fig. 2), and in extreme cases little nipplelike swellings appear, 

 extending to a height of nearly one-fourth of an inch (PL I, fig. 1, k). 

 This will be noticed first upon a medium-sized leaf, gradually 

 spreading to the younger ones, while at the same time the beet almost 

 stops growing and a large number of fibrous roots are sent out (PL 



II, fig. 1). These roots are not confined to two irregular lines as in 

 a healthy beet. 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. 



Many of the species of this genus of leafhoppers produce a 

 discoloration or distortion of the leaves of their food plant. This 

 appears to be of the same nature as the work of the gall- forming 

 species, and is a process little understood. The wrinkling and folding 

 of the leaves by some of the species is very similar in appearance to 

 the work of some gall-forming aphides. Some species also produce 

 a change in color similar to that produced in many galls. 



In the case of Eutcttix strobi (PL I, fig. 2 «, &) and E. scitula on 

 the Chenopodium or on the sugar beet and of E. nigridorsum and FJ. 

 struTninea (PL I, fig. G) on the Helianthus the discoloration appears as 



