12 THE APPLE LEAF HOPPER 



4. This insect occurs upon a large number of plants other than the 



apple ; among them may be mentioned plum, maple, bur- 

 oak, black oak, thorn apple, basswood, hazel, box elder 

 (very abundant), choke cherry, sumac, European birch, cut- 

 leaf birch, syringa, snowball, raspberry, blackberry, bush 

 beans, corn, clover, alfalfa, sugar beets, buckwheat, dahlia, 

 hemp, rhubarb, potatoes, different grasses, etc. 



5. It does not work serious injury to orchard trees, but retards the 



growth of nursery stock, obliging the nurseryman to market 

 his trees, if affected, when four years old, instead of three. 



6. From 1908 observations it would appear to be desirable to 



plant nursery stock at a distance from apple orchards. 



7. The best results as regards remedial measures were obtained 



by the use of shields or screens smeared with tangle-foot. 

 This is effective only against the adults, and might well be 

 used against adults of the first brood. 



8. Sprays containing kerosene are not desirable. 



9. Fish oil soap, 1 lb. in 10 gals, of water, kills adults and young 



if they are not too well concealed in the curled leaves. 



This leaf hopper, extremely common in ^Minnesota, belongs to the 

 Hemipterous family Jossidac. and has been known in this country 

 since the early 50"s, when it was described ( 1853) bv LeBaron under 

 the name of Tcttigonia inali. The insect does not have a complete 

 metamorphosis, but hatches from an egg laid in the petiole, leaf or 

 bark of various plants into a form called a nymph, which resembles 

 the adult very closely. See Fig. 6 of Colored Plate. 



\Mien first hatched the nyni])hs are almost 

 colorless, Imt after they have taken nourishment 

 they become a pale orange or greenish yellow. 

 After hatching from the winter eggs they crawl 

 nj) and settle on the under sides of the young ap- 

 ple leaves. They are active creatures and move 

 rai)i(lly when disturbed. Tlie young hoppers, 

 „. , ,, ^ , witli tlie exception of those in the last nvmphal 



Fig. 1. Second stage ' - ^ 



of K malt, from life, stage, alwavs walk. According: to observations 



much onlarged. Oiigi- .-. . & 



nai. made at tliis Station l)y R. L. Webster in 1907, 



individuals in the last nymphal stage may either walk or hop. Hop- 

 pers in that stage were distinctly seen in several instances, to leap a 



