TREE HOPPERS AND THEIR CONTROL 



9 



7, a, b) hatch later than those of other species, beginning to hatch 

 in early May about the time those of the green-clover species 

 (fig. 7, (?) and the buffalo tree hopper are through hatching. Most 

 hatching takes place on warm, humid mornings, few young nymphs 

 emerging in the afternoon and none at any time when the tempera- 

 ture is below 50° F. On warm mornings, during the hatching period, 

 thousands of the tin} T , white nymphs are often seen emerging from 

 their eggshells in the scars in the bark of twigs (fig. 8, A), water 

 sprouts, and 1-year-old trees. Upon hatching they fall almost im- 

 mediately to the ground or upon whatever plants are present in the 

 orchard. After the eggs have hatched numerous empty, white egg- 

 shells remain protruding from the scars. (Fig. 8, B.) 



Figure 7. — Egg pouches of the tree hoppers : a, Pouch of 

 the dark-colored tree hopper ; &, a pouch of the same with 

 the bark removed to show the eggs ; c, egg pouch of 

 the green-clover tree hopper. X 3 



NYMPHAL STAGES 



After falling to the alfalfa or other plants in the orchard, the 

 young nymphs feed upon these plants, pass through five nymphal 

 stages (fig. 9), and become adult in late June or early July. 

 Throughout the nymphal stages they live by sucking the juices from 

 these plants. They are rarely observed during these stages, since 

 they hide themselves at the very base of the plant upon which they 

 are feeding. They prefer the semidark humid conditions prevailing 

 in the center of alfalfa crowns. Fifty days and ninety days have 

 been recorded as the two extremes for the length of the combined 

 nymphal stages. The average length of time is probably from about 

 60 to 80 days. During the nymphal stages the insects are of the 

 same general shape as they are in the adult stage, but instead of the 



