TWO LEAFHOPPERS INJURIOUS TO APPLE NURSERY STOCK. 25 



Table XIV. — Length ofnymphal stages of the first brood of the rose leaf hopper on nursery 

 apple trees at West Chester, I'a., 1915. 



First brood, May and June. 



Dato 



of 

 hatch- 

 ing. 



First 

 molt. 



First 

 stage. 



Second 

 molt. 



Sec- 

 ond 



stage. 



Third 

 molt. 



Third 

 stage. 



Fourth 

 molt. 



Fourth 

 stage. 



Fifth 

 molt. 



Fifth 

 stage. 



Total 

 nym- 

 phal 

 pe- 

 riod. 



Aver- 

 ago 

 mean 

 tem- 

 pera- 

 ture 

 for 

 nym- 

 phal 



P'': 



nod. 



1915. 

 May 6 

 May 7 



Do... 



Do... 



Do... 



Do... 



Do... 



Do... 

 May 8 

 May 11 



Do... 



1915. 

 May 11 

 May 13 

 May 14 

 ...do.... 

 May 15 

 May 12 

 May 16 

 May 15 

 May 13 

 May 16 

 May 17 



Days. 

 5 

 6 

 7 

 7 

 8 

 5 

 9 

 8 

 5 

 5 

 6 



1915. 

 May 11 

 May 17 

 May 21 

 May 22 



...do 



May 20 

 May 23 



...do 



May 21 



...do 



May 22 



Days. 

 3 

 4 



7 

 8 

 7 

 8 

 7 

 8 

 8 

 5 

 5 



1915. 

 May 21 

 May 24 

 May 29 

 May 28 



...do 



May 26 

 May 29 

 May 30 

 May 27 



...do 



May 28 



Days. 

 7 

 7 

 8 

 6 

 6 

 6 

 6 

 7 

 6 

 6 

 6 



1915. 

 May 28 

 May 30 

 June 4 

 June 2 

 June 3 



...do 



Juno 5 

 June 4 

 June 3 



...do 



...do 



Days. 

 7 

 6 

 6 

 5 

 6 

 8 

 7 

 5 

 7 

 7 

 6 



1915. 

 Juno 7 

 June 8 

 June 12 

 June 10 

 Juno 11 

 June 9 

 Juno 12 

 June 11 

 ...do... 

 June 10 

 June 11 



Days. 

 10 

 9 



8 

 8 

 8 

 6 

 7 

 7 

 8 

 7 

 8 



Days. 

 32 

 32 

 36 

 34 

 35 

 33 

 36 

 35 

 34 

 30 

 31 



"F. 



67.19 



67.33 



68.16 



67.47 



67.79 



67.44 



68.16 



67.79 



67.70 



67.85 



68.29 



Average 



6.-1 



6.3 



6.4 



6.3 



7.8 



33.4 



67.74 

















FIRST BROOD OP ADULTS. 



No attempt was made to obtain definite data on the longevity of 

 first-brood adults. Ninety adults, however, were confined in a Riley 

 cage on a yoimg apple tree on May 31, 1916, and the last leafhoppers 

 died on August 1 ; by this date many of the second-brood nymphs 

 had appeared. Thus, the length of life of the adults of this brood 

 is approximately two months. 



Second Generation. 



SECOND brood of EGGS. 



Length of incubation period. — ^An approximation of the length of 

 the egg stage of second-brood eggs (i. e., the summer eggs) is shown 

 in Table XV. The average length of the period was 25 days; the 

 maximum, 27 days; the minimum, 23 days. 



Table XV. — Length of incubation period of summer eggs deposited by first-brood females 

 of the rose leaf hopper, West Chester, Pa., 1916. 



Four pairs of adults placed in confinement on apple tree July 28, 1916, 4 p. m.; adults removed July 29, 4 p. m. 



Date of removal of newly 

 hatched uymphs. 



1916 



Aug. 21 



Aug. 22 



Aug. 23 



Aug. 24 



Number 



of 

 nymphs 

 removed 



Incuba- 

 tion 

 period. 



Days. 



2.J-25 

 24-26 

 25-27 



Date of removal of newly 

 hatched nymphs. 



1916, 



Aug. 25 



Aug. 26 



Aug. 27 



Aug. 28 



Number 



of 

 nymphs 

 removed. 



Incuba- 

 tion 

 period. 



Days. 



