Biology of the Membra cidae of the Cayuga Lake Basin 187 



CLIMATOLOGY OF THE BASIN 



The climate of the Cayuga Lake basin is undoubtedly influenced, 

 and to some degree regulated, by the water of the lake. Because of its 

 depth the lake water remains cold until late in the summer, and retains 

 the summer heat to such an extent that the surface is rarely entirely frozen 

 over. Li fact a tradition to the effect that the lake freezes over once in 

 every twenty years has been noted by Dudley (1886 :vii) and by Reed 

 and Wright (1909:372), and is verified in a general way by the records of 

 the local weather bureau. Reasonably reliable data tend to show that the 

 lake was entirely frozen over in the winters of 1796, 1816, 1836, 1856, 1875, 

 1884, and 1904. There is also a tradition, persistently advocated by many 

 of the older inhabitants, to the effect that there is an underground 

 connection bet wen Cayuga and Seneca Lakes. L^suall}^ at least two-thirds 

 of Cayuga Lake is open thruout the winter; the shallow water at either 

 end freezes over about the last of December and remains frozen until about 

 the first of March. 



The effect of this on the plant life of the basin has been noted by Dudley 

 as follows (1886: vii): 



The temperature of the lake unquestionably influences the development of vegetation in 

 its immediate vicinity. Plants on its shoies are usually a week later in the Spring than in 

 the neighboring ravines and the warm valley about Ithaca, and a week earlier than on the 

 distant highest hills; and during the first half of November, the blue flowers of Aster Imvis 

 and the white plumes of Aatfr saglthfolius^ still remain in considerable abundance, while they 

 have long ago matured and faded near Ithaca. 



It will be seen that a similar condition has been found in regard to the 

 insects treated in this study, largely due no doubt to the condition of the 

 host plants on which they live. 



The natural influence of the lake on the surrounding temperature, which 

 affects the floral and the faunal forms, has been explained by Von Engeln 

 (1914:347) as follows: 



Where bodies of water of considerable area exist they exert an important equalizing effect 

 on temperature. Water absorbs more heat, holds more heat, is warmed to greater depths, 

 absorbs and radiates heat more slowly than land. Further, 50 per cent of the insolation on 

 water areas is used in evaporating water. This develops a moist blanket of air above and 

 adjacent to the water surfaces that is less subject to marked temperature fluctuations than 

 dry air. The total effect of these differences is to make summers cooler, winters warmer, 

 to prolong the fall season and retard spring, and, also, to check sudden temperature changes 

 in short time periods. 



■So in original. Doubtless Aster sagittif alius. 



