TEEE HOPPERS AXD THEIR CONTROL 



9 



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 tiny, 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.) 



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 be- 

 come adult in late 

 June or early July. 

 Thro u ghou t the 

 nymphal stages they 

 live by sucking the 

 juices from these 

 plants. They are 

 rarely observed dur- 

 ing these stages, since 

 they hide themselves 

 at the very base of the 

 plant upon which they 

 are feeding. They 

 prefer the semidark 

 humid conditions pre- 

 vailing in the center 

 of alfalfa crowns. 

 Fifty days and ninety 

 days have been re- 

 corded as the two ex- 

 tremes for the length 

 of the combined 

 nymphal stages. The 

 average length of 

 time is probablv from 

 about 60 to 80 clays. 

 During the nymphal 

 stages the insects are of the same general shape as they are in the 

 adult stage, but instead of the hard, shell covering they have many 

 bristly spines decorating their backs and many small hairs covering 

 their bodies. (Fig. 9, B-F.) They are of a creamy white to dark- 

 brown color, and have a more or less mottled, greenish appearance. 



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

 the dark-colored tree hopper ; 6, a pouch of the same 

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

 of the green clover tree hopper. X 3 



ADULT STAGE 



Adults (fig. 1; fig. 9, G and H) make their appearance in late 

 June and in July and are present until the last of September, 

 although few are seen after the middle of September. The insects 

 live about two months in the adult stage. During this time they 

 feed to a limited extent upon the alfalfa or other cover crop, but 



