68 JOURNAL OF ECONOMIC ENTOMOLOGY " [Vol. 14 



compared with 142 nymphs reared from a single female appearing at the 

 time of the spring flight. 



Experiments were conducted to determine what time of the day the 

 eggs are laid. Potato plants in large pots were exposed daily during 

 the egg laying season and a careful count of the number of nymphs 

 hatching noted. The plants were carried to a near-by potato plot and 

 left there for twelve hour periods. When not in use they were kept free 

 from exposure to the adults. Plants exposed from 5 p. m. to 9 a. m. 

 hatched the greatest number of nymphs, which indicated that oviposi- 

 tion occurs for the most part at night. 



Host Plants 



In order to determine whether or not a complete generation could be 

 reared on some of the plants upon which Empoasa maJi had been ob- 

 served feeding, a number of experiments were conducted with curly 

 dock (Rumex crispus), Carolina poplar {Popnlns alba), pig weed 

 (Chenopodiiini album), and broad leaf plantain (Plantago major). All 

 of the above gave negati^'e results except curly dock from which a com- 

 plete generation was reared. In addition to curly dock the potato 

 leafhopper has been bred on apple, bean and potato. The writer has 

 collected nymphs from Carolina poplar, sumac {Rhus hirta), rhubarb, 

 hollyhock and dandelion. It is possible that the adults feed somewhat 

 promiscuoush' and may oviposit in plants that are tmable to sustain 

 the young, but the supposed long list of host plants may have to be re- 

 duced. Strangely enough we have never collected n_\'mphs from broad 

 leaf dock {Rumex obtusifolius) . 



The importance of curly dock as a wild host was brought 

 forcibly to our attention bv the death of the late potato vines in August. 

 Adults and nymphs were found on these plants until frost and it is 

 probable that this host may ser\'e as a connecting link between late 

 potatoes in the fall and early potatoes in the spring. The plant affords 

 a very succulent growth and is one of the earliest to appear in the spring 

 and is very resistant to frost. The importance of this weed as a host 

 plant is worthy of further study. 



President Wilmon Newell: The next paper is by Air. John R. 

 Eyer, on "The Influence of Leaf-hopper Control on Potato Yields." 



