356 



Journal of Agricultural Research 



Vol. III. No. 4 



and because of the variation in minimum temperatures existing between 

 the winter of 1912-13 and that of 1913-14 and its relation to hibernation, 

 Table VI, showing the minimum temperatures, is given. 



Table VI. 



-Average minimum, temperatures at Tempe, 

 igi2-i3 and igi3-i4 



Ariz., during the winters of 



Dec. I to 10 



II to 20 



21 to 31 



Jan. I to II 



10 to 20 



2 1 to 3 1 . 



Feb. I to 10 



11 to 21 



21 to 28 



Average minimum for 3 months 

 Actual lowest temperature 



While it will be noted in Table VI that there was a difference of 

 nearly 6 degrees in the average minimqm of the three months, December 

 1912, and January and February, 1913, as compared with the same 

 three months of 1913-14, yet the most striking difference and the one 

 that influenced hibernation is noted between December 1 1 and February 

 I of the two years. For the former winter, the one during which the 

 species hibernated, the average minimum from December 1 1 to January 

 31 was 30.3° F., and the actual lowest was 12° F., as against an average 

 minimum of 40.3° F. and an actual lowest of 29° F. for the same period 

 of the winter 191 3-14, during which time the species was continually 

 active. 



During the winter of 1912-13 the hibernating period lasted about two 

 months. Just how long it may last any other winter will depend upon 

 the temperature; if, as was shown to be the case last winter, the tempera- 

 ture remains high enough, the insect will not go into hibernation. At 

 Tempe the adults have been found particularly abundant at the base of 

 bunch grass {Sporobolus airoides) and they are also found hiding below 

 rubbish, leaves, etc., at the base of plants such as will provide them with 

 green food on the first warm days of spring. 



In Mississippi Mr. Gibson has found that the hibernating period lasts 

 from December until March and that the chief protection for the dormant 

 adults consists of bunches of Andropogon spp., in the clumps of which 

 he has counted as many as 63 adults. At Nashville, Tenn., he has 

 observed hibernating adults active by March 1 1 . 



SUMMER -ACTIVITY 



In Arizona hibernating adults that come forth during the first part of 

 February deposit eggs soon thereafter, and during the latter part of 

 March, April, and the first part of May die off. Young of the first genera- 

 tion, whether they come from overwintering eggs or from eggs of hiber- 

 nating adults, appear during the month of March. There are from three 



