withering, and curling of leaves. Because of the difficulty in observing or evaluat- 
ing the damage to trees, very little is known of its magnitude or importance. The 
probability is that it is grossly underestimated. These insects, in fact, may contrib- 
ute significantly to the general unproductiveness of many stands of valuable 
hardwoods in the Eastern United States. Many species are also vectors of destruc- 
tive plant diseases, especially diseases of viral, mycoplasmal, or rickettsial origin. 
Some species of leafhoppers spend the winter in the egg stage; others, as adults. 
Nymphs usually hatch from overwintering eggs in May or June, and then feed on 
new, tender leaves. Overwintering adults emerge during the first warm days in 
spring and lay eggs as soon as the leaves of their hosts are fully developed. Nymphs 
hatch in about 10 days. As a rule there are one or two generations per year; 
sometimes, more. 
Forest and shade trees serve as hosts for many species of Erythroneura, Em- 
poasca, and Typhlocyba (295). Several species of /diocerus feed on willow and 
poplar. Various species of Macropsis feed on poplar, willow, and honeylocust. 
Certain species of Scaphoideus, Gyponana, and Ponana occur on American elm; 
oaks are infested by species of Alebra, Eutittix, and Penthimia. This is only a 
partial listing of genera and species known to attack trees; the total number is far 
greater. 
The most important leafhopper as far as forest and shade trees are concerned Is 
the whitebanded elm leafhopper, Scaphoideus luteolus Van Duzee, the vector of 
elm phloem necrosis, a mycoplasmal disease of American elm (43). Adults are 
difficult to separate from those of closely related species, but not so the nymphs 
(fig. 20). After the second instar, practically all of the nymphs are dark brown with 
a transverse white band across the dorsum. This band lies just behind the thorax and 
covers the first two and part of the third abdominal segments. The species is widely 
distributed in the Eastern United States, from New York west to Kansas, Nebraska, 
and Iowa, and south to Georgia and Alabama. 
F-531900 
Figure 20.—Adult and nymph of the 
whitebanded elm leafhopper, 
Scaphoideus /uteolus. 
70 
