TWO LEAFHOPPERS INJURIOUS TO APPLE NURSERY STOCK. 17 



Table XJ. — Length of incubation period of third-brood eggs of the apple leafhopper, 



West Chester, Pa., 1915. 



Cage No. 1.— SIX PAIRS OF ADULTS PLACED ON APPLE TREE AUG. 6, 1915, 8 A.M.; 

 ADULTS REMOVED AUG. 6, 4 P. M. 



Date of removal of newly hatched nymphs. 



Number 



of 

 nymphs 

 removed. 



Incuba- 

 tion 

 period. 



Average 

 tempera- 

 ture for 

 entire 

 period. 



1915. 



Aug. 15, 4 p. m. 

 Aug. 16, 4 p. m. 

 Aug. 17, 4p.m. 



Average.. 



Days. 

 8.6- 9.3 

 9.6-10.3 

 10.6-11.3 



9. 6-10. c 



°F 

 75.95 

 76.40 

 76.00 



76.11 



Cage No. 2.— TEN PAIRS OF ADULTS PLACED ON APPLE TREE AUG. 9, 1915, 4 P. M. 

 ADULTS REMOVED AUG. 10, 4 P. M. 



1915. 



Aug. 19, 4 p. m. 

 Aug. 20, 4 p. m. 

 Aug. 21, 4 p. m. 

 Aug. 22, 4 p. m. 



Average . . 



Days. 

 8-10 

 9-11 

 10-12 

 11-13 



.5-11.5 



75.15 



75.00 

 74.87 

 75.07 



75.02 



Cage No. 3.— TWENTY-FIVE PAIRS OF ADULTS PLACED ON APPLE TREE AUG. 13, 1915, 

 4 P. M.; ADULTS REMOVED AUG. 14, 3 P. M. 



Aug. 23, 4 p. m. 

 Aug. 24, 4 p. m. 

 Aug. 25, 4 p. m. 

 Aug. 26, 4 p. m. 

 Aug. 27, 4 p. m. 



Average... 



1915. 



Days. 

 8-10 

 9-11 

 10-12 

 11-13 

 12-14 



10-12 



"F 

 74.65 

 74.95 

 74.70 

 74.57 

 73.89 



74.55 



Table XII. — Length of nymphal stages of the third brood of the apple leafhopper at West 



Chester, Pa., 1915. 









THIRD ] 



BROOD, i 



UJGU 



ST AND 



SEPTEMBER. 

































Aver- 



























age 



























mean 



Date 









Sec- 

 ond 

 stage. 















Total 



tem- 



of 



First 



First 



Second 



Third 



Third 



Fourth 



Fourth 



Fifth 



Fifth 



nym- 

 phal 

 pe- 



pera- 



hatch- 

 ing. 



molt. 



stage. 



molt. 



molt. 



stage. 



molt. 



stage. 



molt. 



stage. 



ture 

 for 























riod. 



nym- 

 phal 



















































rFod. 



1915. 



1915. 



Days. 



1915. 



Days. 



1915. 



Days. 



1915. 



Days. 



1915. 



Days. 



Days. 



°F. 



no 1 . 2 



Aug. 14 



2 



Aug. 17 



3 



Aug. 20 



3 



Aug. 22 



2 



Aug. 27 



5 



15 



74. 44 



Aug. 16 



4 



Aug. 19 



a 



Aug. 21 



2 



Aug. 25 



4 



Aug. 30 



5 



18 



73.10 



Do.. 



Aug. 15 



3 



...do 



4 



Aug. 22 



3 



...do 



3 



Aug. 31 



6 



19 



72.55 



Do.. 



Aug. 16 



4 



...do 



3 



Aug. 23 



4 



Aug. 27 



4 



Sept. 3 



7 



22 



72.32 



Aug. 14 



Aug. 15 



1 



Aug. 18 



3 



Aug. 21 



3 



Aug. 24 



3 



Aug. 30 



6 



16 



72.50 



Aug. 16 



2 



Aug. 19 



3 



Aug. 22 



3 



Aug. 25 



3 



Aug. 31 



6 



17 



71.94 



Do.. 



...do.... 



2 



...do 



3 



...do 



3 



...do 



3 



Sept. 1 



7 



18 



71.78 



Do.. 



...do.... 



2 



...do 



3 



Aug. 23 



4 



Aug. 27 



4 



Sept. 2 



6 



19 



71.52 



Do.. 



Aug. 17 



3 



...do 



2 



Aug. 24 



5 



Aug. 26 



2 



Sept. 1 



6 



18 



71.78 



Aug. 17 



Aug. 20 



3 



Aug. 23 



3 



Aug. 26 



3 



Aug. 31 



5 



Sept. 6 



6 



20 



71.76 



Do.. 



...do.... 



3 



Aug. 22 



2 



Aug. 25 



3 



...do 



6 



6 



20 



71.76 



Do.. 



Aug. 21 



4 



Aug. 23 



2 



...do 



2 



Sept. 1 



7 



...do.... 



5 



20 



71.76 



Do.. 



...do.... 



4 



...do 



2 



Aug. 26 



3 



6 



Sept. 7 



6 



21 



72.09 



Do.. 



Aug. 20 



3 



Aug. 22 



2 



Aug. 25 



3 



...do 



7 



Sept. 6 



5 



20 



71.76 



Average 



2.8 



2.7 



3.1 



4.2 



5.8 



18.7 



72.21 



132816°— 19- 



