290 Report of the Department of Entomology of the 



of 125 degrees — a daily average of 4 degrees ; September tempera- 

 tures were 59 degrees above normal — a daily excess of 1.7 de- 

 grees. In the months when growth is most active — May to Sep- 

 tember — there was a deficiency of 148 degrees — 1 degree daily. 

 The amount of precipitation for May, August and September 

 was above the normal while June and July were deficient in rain- 

 fall. From the middle of July until the end of September there 

 was an excess of rainfall and cloudy weather combined with the 

 low temperatures. There were only four clear days between July 

 15th and 31st and August had only one clear day, the others being 

 cloudy or partly cloudy. The percentage of sunshine during 



August was 42 23 per ct. below normal — while the rainfall 



was 4 inches or 1.01 inches above normal, 40 per ct. more than 

 in a normal year. September had 11 clear days, 53 per ct. of 

 sunshine, 8 per ct. departure from normal, and an excess rain- 

 fall of 0.13 inch or 4 per ct. above the average. These abnor- 

 mal weather conditions were unfavorable to plant growth, and ap- 

 peared to be especially detrimental to the grape leaf-hopper since 

 it prevented a second summer brood and apparently interfered 

 with the health of the nymphs as well as the adults. This has re- 

 sulted in a greatly decreased number of hoppers going into winter 

 quarters during the fall of 1912 compared with the number in the 

 preceding autumn. Judging from the conditions prevailing dur- 

 ing the autumn many acres of vineyards are in danger of severe 

 infestation in the spring, although not as many as in 1912. The 

 unfavorable weather conditions interfered with the proper ripen- 

 ing of the fruit in many vineyards, irrespective of their conditions 

 with regard to the insect, but the interference with the ripening 

 and quality was most marked when the leaf-hopper injury was 

 severe. 



BIOLOGICAL STUDIES. 



HIBERNATION HABITS. 



The adult leaf-hoppers remain on the vines until most of the 

 foliage drops to the ground. During autumn they may be ob- 

 served among fallen leaves, cover crops, weeds and grass that may 



