February, '15] 



PRESIDENTIAL ADDRESS, DISCUSSION 



91 



Albany there is an extensive sandy area. Land of this character 

 absorbs large amounts of heat in the daj^ime and gives it off at night, 

 thus preventing during the active groT\ing season, dangerously low 

 night temperatures and permitting a greater extension of the upper 

 austral life zone than would be possible otherwise. For example, the 

 well-knoT\'n southern Sphecius speciosus has been taken for several 

 years in succession on the sand}" plains west of Albany. 



We have endeavored to trace the connection between climatic con- 

 ditions and insect outbreaks, because we realize that if we could say 

 to our farmers: '^Certain weather conditions are favorable or unfa- 

 vorable for the development of injurious insects," we had something 

 of practical value, pro^dded it was not carried too far. We are satisfied 

 that abnormally low temperatures continued late in the season mean 

 favorable conditions for outbreaks of apple plantlice. 



Another interesting matter is in connection ^dth the elm-leaf beetle. 

 In 1912 and again in 1914, in a little "village (Xassau) fourteen miles 

 from Albany and having an elevation of about 400 feet, we have had 

 a large number of elms under personal observation. In the early 

 spring of both seasons, elm-leaf beetles appeared in numbers rather 

 abundantly and deposited many eggs, a condition preliminary to exten- 

 sive and serious injuries, which latter failed to develop as expected. 

 We carefully examined the temperature records for the month of June, 

 covering a period of ten years, and found in the case of the two yesns 

 mentioned above, a marked decrease in the average temperatures dur- 

 ing the middle ten days of the month, namely June 11 to 20 inclusive. 

 This is a time when, under normal conditions, in our latitude, egg- 

 laj-ing should be at its maximum. It is necessary, in our estimation, 

 that there should be a coincidence between the period of low tempera- 

 tures and the time when oviposition is at its height, otherwise these 

 vital functions, such as the deposition of eggs, their hatching and the 

 development of the 3'oung larvae, may simply be delayed rather than 

 inhibited. Under our conditions it would appear that when the sum 

 of the maximum and minimum temperatures (F.) for a ten-day period 

 for or about the middle of June does not exceed 1,250, the proba- 

 bilities are that egg-lajdng will be checked and that an unusual mor- 

 tahty will occur in both eggs and young grubs. This is simply a ten- 

 tative proposition and is a hne of investigation which must be followed 

 with, caution. 



A little farther east from Xassau, at an elevation of approximately 

 800 feet, and surrounded by ridges running close to 2,000 feet, there 

 seems to be relatively little injury from this insect, presumably due to 

 the fact that the minimum spring temperatures prevent a normal and 

 vigorous development. 



