438 Report of the Department of Entomology of the 



Weather influences. — Weather greatly affects the activities and 

 numbers of the insect. The influence of temperature in the move- 

 ments of adults and egg deposition have previously been shown. 

 The following notes are of interest as showing the effects of storms 

 and other conditions upon other habits as well as the numbers of 

 the insect. On March 26, 1910, adults emerged from winter quarters 

 and appeared on pear trees and during the first week of April 

 deposited thousands of eggs. On April 7, 1910, a cold rain occurred 

 at Lockport which coated the trees with ice and on the following 

 day few " flies " were observed upon the trees. A small number 

 of these adults were caught in the ice or dropped to the ground 

 where they perished in the soft earth beneath the trees. Many 

 of them, however, were apparently able to find some protection and 

 on April 20 the trees were reinf ested. In 191 1 a warm period occurred 

 during the week ending March 9, and " flies " appeared in con- 

 siderable numbers. During the following night a drenching rain 

 washed thousands of the " flies " to the soft ground where they 

 died. On April 8, 1912, the adult psyllas which were out in full 

 numbers in the tops of the trees were caught by a sudden 

 change of weather and many, numbed by the cold, dropped to the 

 muddy ground beneath from which they were unable to extricate 

 themselves. 



In a letter dated March 31, 1913, Mr. F. S. Hayden of Wyoming, 

 N. Y., stated that a cold, freezing rain on March 26 had coated the 

 pear trees in his orchard with ice, and during the warmer days 

 which followed only from one-third to one-fifth of the original infes- 

 tation of adult psyllas appeared on the trees after the storm. On 

 March 22, 1913, according to Mr. A. B. Buchholz of the State Bureau 

 of Horticulture, a sudden drop in the temperature so numbed the 

 " flies " that they dropped to the ground and later collected in 

 swarms about the " collar " of the trees. In the Collamer orchard 

 at Hilton we have frequently observed in early spring large numbers 

 of the adults under weeds and rubbish beneath the trees or at the 

 " collars " of trees near the surface of the ground. Their presence in 

 these situations we have attributed to the same cause. Mr. L. F. 

 Strickland, also of the State Bureau of Horticulture, reported that 

 in Niagara county a heavy driving rain on March 24, 1913, washed 

 thousands of " flies " from pear trees and in some instances the 

 insects appear to have almost entirely disappeared. The actual 



