THE WINTER OF 1918-'19 AND THE ACTIVITIES OF 



INSECTS WITH SPECIAL REFERENCE TO THE 



CLOVER LEAF- WEEVIL 



(Hypera punctata Fab.) 



Glenn W. Herrick. 



Our knowledge of the factors governing the ability of insects 

 to pass successfully through any given winter conditions is very 

 meager. Apparently some winters are very destructive to 

 insect life and bring about a high mortality in the stages that 

 attempt to survive this period while other winters are favorable 

 to the survival of the eggs, larvae, pupae, or imagos as the case 

 may be. The winter of 1918-1919 was certainly a very open and 

 abnormally warm one all over New York State ; but it is appar- 

 ent, from studies made regarding the effect of heat and cold on 

 insect life, that the comparative degrees of humidity, as well as 

 of temperature, must be taken into account if correct general- 

 izations are to be made. For example, . as Pierce^ says: "A 

 creature which can stand a certain degree of cold at a given 

 humidity may be absolutely unable to stand that same tem- 

 perature at another degree of saturation or relative humidity." 

 Thus there have arisen conflicting interpretations of climatic 

 effects on insects made by different investigators in different 

 localities because they were working under very different 

 degrees of humidity of which no account was taken. It will 

 perhaps not be out of place to give a brief summary of the 

 weather conditions from November to April inclusive as recorded 

 by the weather station at Cornell University: 



November, 1918. 

 "Weather conditions throughout November, 1918, were warm and 

 pleasant, for the most part, with average temperatures generally above 

 the normals in all sections, but the month was a very dry one in all 

 districts, except at few points in the northern part of the State." 



December, 1918. 

 "Reports from all sections show that the month was unusually 

 mild with an average excess of warmth of about four and one-half 

 degrees, which is in marked contrast to the severe December of a year 

 ago. A brief spell of zero weather was experienced in the Adirondacks 

 during the first week and again in the northern counties during the 



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