18 



BULLETIN 805, U. S. DEPARTMENT OF AGRICULTURE. 



THIRD BROOD OF NYMPHS. 



Length of stages. — The average nymphal period was 18.7 days; 

 the maximum, 22 days; the minimum, 15 days. (See Table XII.) 



THIRD BROOD OF ADULTS. 



Attempt to rear a fourth brood of nymphs. — Third-brood adults 

 which were reared in confinement were placed on young apple trees 

 in globe cages in an attempt to rear a fourth brood of nymphs. 

 Four experiments were carried out, pairs of adults being confined on 

 August 24, September 14 and 30, and October 1. None of the adults 

 was observed to mate and not a single fourth-brood nymph 

 developed. The foliage was examined several times covering a 

 period of six weeks or more after the adults were confined. 



Number of winter eggs deposited. — Four globe cage experiments 

 were conducted to determine whether the third and last brood 

 adults of the apple leafhopper deposited winter eggs in the bark of 

 apple trees. Pairs of adults were confined in four separate cages 

 on August 24, September 14, September 30, and October 1. They 

 were allowed to remain undisturbed on the trees until December 10, 

 when the trees were brought into the laboratory and carefully 

 examined for winter eggs under the bark. Not a single winter egg 

 was found on any of the four trees. 



Table XIII. — Daily maximum, minimum, and average temperatures taken at West 

 Chester, Pa., from May 12 to Sept. 18, 1915. 



Day of 



May. 



June. 



July. 





August 





September. 

































month. 



Maxi- 



Mini- 



Av- 



Maxi- 



Mini- 



Av- 



Maxi- 



Mini- 



Av- 



Maxi- 



Mini- 



Av- 



Maxi- 



Mini- 



Av- 





mum. 



mum. 



erage. 



mum. 



mum. 



erage. 



mum. 



mum. 



erage. 



mum. 



mum. 



erage. 



mum. 



mum. 



erage. 





°F. 



o K 



°F. 



°F. 



°F. 



°F. 



°F. 



°F. 



°F. 



°F. 



°F. 



°F. 



°F. 



°F. 



°F. 



1 









80 

 60 

 59 

 80 

 84 

 75 



64 

 54 

 48 

 59 

 70 

 70 



72 



57 



53.5 



69.5 



77 



72.5 



86 

 84 

 88 

 84 

 80 

 76 



76 

 68 

 76 

 75 

 72 

 68 



81 



76 



82 



79.5 



76 



72 



96 

 91 

 75 

 84 

 83 

 80 



82 

 79 

 67 

 76 

 77 

 70 



89 

 85 

 71 

 80 

 80 

 75 



72 

 73 

 81 

 83 

 84 

 86 



66 

 66 

 66 

 72 

 74 

 76 



69 



2 









69.5 



3 









73.5 



4 









77.5 



5 









79 



6 



74 



67 



70.5 



81 



7 



77 



65 



71 



84 



71 



77.5 



82 



72 



77 



68 



63 



65.5 



86 



74 



80 



8 



70 



60 



65 



80 



70 



75 



80 



68 



74 



84 



72 



78 



86 



71 



78.5 



9 



63 



54 



58.5 



76 



66 



71 



83 



66 



74.5 



H2 



70 



76 



86 



78 



82 



10 



66 



55 



60.5 



76 



61 



68.5 



86 



76 



81 



80 



70 



75 



90 



76 



83 



11 



68 



58 



63 



84 



74 



79 



80 



73 



76.5 



80 



72 



76 



86 



78 



82 



12 



72 



60 



66 



88 



75 



81.5 



87 



72 



79.5 



79 



71 



75 



84 



74 



79 



13 



80 



59 



69.5 



86 



78 



82 



84 



75 



79.5 



85 



78 



81.5 



88 



82 



85 



14 



81 



60 



70.5 



89 



76 



82.5 



85 



71 



78 



84 



73 



78.5 



88 



80 



84 



15 



79 



54 



66.5 



84 



72 



78 



84 



74 



79 



84 



74 



79 



86 



80 



83 



16 



62 



50 



56 



83 



75 



79 



89 



74 



81.5 



-. 85 



77 



81 



88 



76 



82 



17 



71 



62 



66.5 



84 



74 



79 



91 



83 



87 



75 



68 



71.5 



88 



74 



81 



18 



61 



50 



55.5 



83 



77 



80 



92 



82 



87 



70 



58 



64 



81 



70 



75.5 



19 



20 



74 



52 



63 



83 



76 



79 5 



90 



82 



86 



76 



64 



70 









75 



64 



69 5 



80 



73 



76.5 



79 



72 



75.5 



82 



65 



73.5 







21 



66 



59 



62 5 



77 



65 



71 



78 



68 



73 



76 



71 



73.5 







22...'..'. 



23 



24 



84 



69 



76 5 



65 



60 

 61 



62.5 

 65 



84 



74 



79 



83 



72 



77.5 





1 



72 



66 



69 



69 



81 



68 



74.5 



83 



73 



78 









70 



58 



64 



75 



60 



67.5 



80 



74 



77 



84 



72 



78 









25 



26 



27 



28 



29...... 



30 



31 



76 



68 



72 



81 



66 



73 5 



84 



74 



79 



76 



68 



72 









77 



60 



64 

 66 



68.5 

 71.5 

 68 



84 



69 



76 5 



84 



72 



78 



76 



70 



73 









79 

 70 



78 



68 

 65 



73 



71 5 



82 



69 



75 5 



70 



60 



65 









78 



82 



74 



78 



66 



62 



64 









69 

 79 



80 



63 



66 



75 

 75 



78 

 80 



67 



72 5 



86 



78 



82 



66 



60 



63 









71 

 70 



' 75 



77 5 



90 



80 



85 



74 



68 



71 













91 



74 



82.5 



68 



57 



62.5 





















