10 



BULLETIN 254, IT. S. DEPARTMENT OP AGRICULTURE. 



From the notes made by Mr. Wildermuth at Tempe, Ariz., in 1913, 

 for the first spring generation the average length of the nymphal 

 stage during March and April is shown to be 40 days, a few days less 

 than that obtained the following year by the writer. (Table V.) 



Table V .—Length of nymphal stage of the sharp-headed grain leaf hopper, Tempe, 



Ariz., 1913. 



Nymphs emerged 

 from egg. 



Adults emerged 



from last 

 nymphal molt. 



Length of 



nymphal 



stage. 



Mar. 18 



Mar. 24 



Mar.27 



Mar. 24 



Average . 



Apr. 20 

 May 5 



do 



MavlO 



Days. 

 33 



42 

 39 



47 



40.25 





HIBERNATION AND WINTERING. 



Prof. Osborn 1 states that " hibernation seems to occur in all stages 

 from the egg to the adult, although the great majority must pass the 

 winter in the egg stage." At Tempe, Ariz., the writer searched 

 diligently during January, 1914, for all stages of the species but 

 found only adults. No eggs were deposited in cages either in or out 

 of doors until February 4. Dissections of adult females during 

 January showed them to be full of immature eggs. An experiment 

 was carried on in which young nymphs were submitted to a tempera- 

 ture of 35° F. for 18 hours, at the end of which all nymphs were 

 dead, showing that it is improbable that young nymphs could ever 

 withstand the winter. Mr. F. H. Gates, another assistant of the Bu- 

 reau of Entomology at Tempe, reports having taken adults on a 

 number of days during November and December, 1914, and January, 

 1915. On December 15 he took several nymphs which were prob- 

 ably in the fourth or fifth instar. From his observations it would 

 seem that the nymphs which had attained the fourth or fifth instar 

 by late fall might survive the winter, although up to December 15 

 there had been no really cold weather at Tempe, the minimum tem- 

 perature recorded to that date having been 28° F. At Charleston, 

 Mo., during November and December no eggs or nymphs could be 

 found, while the adults were present and active on warm days. It 

 seems safe, therefore, to assume that the species winters over princi- 

 pally in the adult stage throughout the Southern States and in all 

 probability the same holds true throughout the country. 



GENERAL ACTIVITIES OF THE ADULTS. 



The adults are exceedingly quick of movement, and might well be 

 described as restless. They are easily disturbed or frightened and 



Op. cit., p. 58. 



