246 



Empoasca mali, Le B. [R.A.E., A, vii, 278'. During the author's 

 obser\-atit)ns two other leaf-hoppers, Dcltocephalits inimicus and 

 Cicadiila scxnotata, were found on the plants. The difference of attack 

 by leaf-hoppers and the tarnished plant bug [Lyi^iis pratensis] is 

 described. 



The hopperdozcr was found useless against E. mali, which could 

 only be controlled by spraying with 2 to 1 or pure kerosene. The 

 latter did not injure the plants, the reason for which was later 

 determined by Moore [loc. cit., \'\, 200]. 



Haktzell (A.). Further Notes on the Life-history of the Potato 

 Leaf-hopper iEmpoasca mali, Le Barcn). — //. Econ. Ent., Concord, 

 X. H., xiv, no. 1, February 1921, pp. 62^68, fig 1. 



In continuing the study of E>npoasca mali, LeB. (potato leaf-hopper) 

 'R.A.E., A, ix, 31], it has been found that the over-wintering females 

 represent a mixed population, some of them probably being the remnant 

 of the summer generation of the previous year that had emerged 

 too late to complete egg-laying. During the growing season of 1920 

 one complete and a partial second generation occurred. Field counts 

 indicated about half the number of leaf-hoppers as compared with the 

 previous year. Adults of the summer generation were abundant 

 in the last week in July, but the second brood was insignificant as 

 compared with the first. The development of this generation was 

 probably influenced by the dying of the potato plants during the latter 

 half of August. 



The remaining adults migrated to curly dock. Insects in all stages 

 were found on this plant as late as 28th October ; when the food-plant 

 failed, the adults entered into hibernation. Attempts were made to 

 rear a complete generation on Carolina poplar {Populus alba), pig-weed 

 {Chenopodium album), broad-leaf plantain {Plantago major) and 

 curly dock (Rumex crispus), but they were only successful on the last- 

 named. This food-plant may serve as a connecting link between 

 the late potatoes in the autumn and early potatoes in the spring. 



The insect has also been bred on apple, bean and potato. Nj^mphs 

 have been collected from Carolina poplar, sumac {Rhus hirta), rhubarb, 

 hollyhock and dandelion. The adults probably feed somewhat pro- 

 miscuously, and may oviposit on plants that are unable to sustain the 

 earlv stages. 



Ever (J. R.). The Influence of Leaf-hopper Control on Potato Yields. 



— //. Econ. Enl., Concord, X.H., xiv, no. 1, February 1921, 

 pp. 69-71. 



Experiments made in 1919 indicate that Bordeaux mixture partially 

 reduces hopper-burn and increases the yield by 29 bushels per acre ; 

 Bordeaux-lime (4:8: 50) controlled hopper-burn more effectively, 

 but the yield was 12 bushels less. Extensive experiments were carried 

 out in 1920, in which hopper-burn was reduced to a minimum by the 

 application of Bordeaux 4:8: 50 and nicotine 1 : 800. The average 

 gain, as compared with standard Bordeaux, is about 6 bushels per acre, 

 but in view of the additional cost of the nicotine, the advisability of 

 its use in regions where there is comparatively little sunshine during 

 the growing season is questionable. 



