434 Report of the Department of Entomology of the 



Table VII. — Activities of Hibernating Brood of Pear Psylla and Conditions 

 of Trees During the Spring of 1913. 



Date. 



Mar. 14 



15 

 16 

 17 

 18 

 19 

 20 

 21 

 22 

 23 

 24 

 25 

 26 

 27 

 28 

 29 

 30 

 31 



April 



1 

 2 

 3 

 4 

 5 

 6 

 7 

 8 

 9 

 10 



11 

 12 

 13 

 14 



15 



16 

 17 



18 

 19 

 20 

 21 

 22 

 23 

 24 

 25 

 26 

 27 

 28 



Activities of insects. 



" Flies " appear on 



buds 



" Flies " very active. 



Eggs being laid. 



" Flies " have disap- 

 peared 



Most eggs 



Many collapsed eggs 



Conditions of trees. 



Daily 

 mean 

 tem- 

 perature. 



Eggs hatching. 

 Few nymphs. . 



Many nymphs . 



Cluster buds break- 

 ing 



Cluster buds sepa- 

 rating 



Leaf buds opening . 



Blossom buds opening 



°F. 

 57 

 53 

 35 

 23 

 37 

 49 

 54 

 51 

 45 

 33 

 40 

 49 

 44 

 33 

 27 

 38 

 50 



49 



39 

 41 

 47 

 60 

 52 

 34 

 31 

 36 

 38 



38 

 45 

 49 

 45 



46 

 50 

 52 



46 

 55 

 52 

 33 

 43 

 52 

 63 

 68 

 66 

 69 

 60 

 51 



Weather. 



Clear 



Partly cloudy . . 



Cloudy 



Cloudy 



Partly cloudy . . 

 Partly cloudy . . 



Cloudy 



Cloudy 



Clear 



Cloudy 



Cloudy 



Cloudy 



Cloudy 



Cloudy 



Partly cloudy. 



Clear 



Clear 



Cloudy 



Clear 



Cloudy 



Cloudy 



Cloudy 



Cloudy 



Partly cloudy. 



Clear 



Clear 



Cloudy 



Cloudy 



Cloudy 



Partly cloudy. 

 Clear 



Clear 



Clear 



Clear 



Cloudy 



Cloudy 



Partly cloudy. 



Clear 



Cloudy 



Cloudy 



Cloudy 



Clear 



Clear 



Clear 



Cloudy 



Cloudy 



Rain or 



snow. 



.03 

 Trace snow 

 1 . snow 



Trace 

 Trace 

 Trace 



.31 

 1.15 

 1.35 



.99 



.36 

 Snow 



.15 



.11 



.29 

 .13 



. 5 snow 

 Snow 



.72 

 .6 



.27 



.96 

 .83 



and in 1912 few adults were seen until April 11. The earliest 

 extensive migration of which record was obtained in any year occurred 

 on March 14, 1913, but many " flies " were destroyed by storms 

 and extreme cold later in the month. The final emergence of the 

 " flies " in the spring from their winter quarters and their subsequent 

 activities for the four-year period are given in Tables IV-VII. 



