292 Report of the Department of Entomology of the 



to reveal any of the insects in green cover crops or among fallen 

 grape leaves as these appear to be pressed too tightly by the snow 

 for the hoppers to survive. Usually such green cover crops are 

 not high enough to catch many leaves and so are not conducive to 

 sheltering the leaf-hoppers. Cover crops examined were cow- 

 horn turnips, wheat, clover, rye and vetch. Chickweed (Stellaria 

 media) in vineyards has also not been found to shelter the insects. 



effects of moisture and cold on insects. 



The leaf-hopper survives the winter in greatest numbers in dry 

 locations and is absent from low-lying land, such as the clay and 

 some of the loam soils. On the higher soils — the gravel and large 

 areas of the loam soils — there is no winter flooding and the rains 

 soon drain away, thus offering the driest winter quarters to be 

 found in the grape belt. Here the leaf -hopper abounds. Although 

 wet situations are not favorable to them, the insects are not easily 

 drowned. They are able to walk on water for a considerable time 

 without drowning. They are even able to rise on wing from the 

 surface of water, at least in the summer when the temperature is 

 higher, and no doubt are able to withstand considerable water dur- 

 ing the winter. Notwithstanding all these protective adaptations 

 they instinctively seek dry winter quarters. This species is also 

 able to withstand considerable cold, and it does not seem as though 

 our normal winters influence appreciably the numbers of the leaf- 

 hoppers. The winter of 1911-12 was extremely severe. Low 

 temperatures prevailed, as well as other unfavorable factors such 

 as winter rains followed by snow, which soaked and packed down 

 leaves and froze them together, while the temperature at one time 

 dropped to 18° below zero and later to 14° below. Yet with all 

 these apparently unfavorable conditions the numbers of adults 

 appearing in the spring did not indicate a high mortality. 



SPRING FOOD PLANTS. 



From the first warm days in the spring until the grape foliage 

 appears, the leaf-hoppers feed, especially during the warmer days, 



