348 Journal of Agricultural Research voi. m. No. 4 



being reduced in length. Other body spines much more numerous than in first st^e, 

 but reduced in proportionate size. 



Stage III (PI. XLIII, fig. 4). — Length, 2.9 mm. (2.6 103 mm.), average of 10 speci- 

 mens. Head, thorax, abdomen, and appendages dark straw color, cologne-earth patch 

 in some specimens especially pronounced. Dorsal projections more fleshy and con- 

 taining a greater number of lateral spines. Prothoracic shield beginning to develop. 

 Wing pads faintly visible. 



Stage IV(Pl.XI,III,fig. 5). — Length, 3.8 mm. (3.5 to 4.1 mm.), average of lospeci- 

 mens. Head, thorax, abdomen, and appendages greenish straw color. Dark patch 

 on thorax and abdomen becoming dark brown, almost black. The color varies 

 greatly, however, some specimens being light green and others ver>' dark throughout 

 the stage. Dorsal projections in this and fifth stage quite fleshy, lateral spines numer- 

 ous. Prothoracic shield with posterior projection extending nearly to end of thorax. 

 Wing pads clearly defined. 



Stage V (PI. XLIII, fig. 6). — Length, 4.8 mm. (4.5 to 5 mm.), average of 10 speci- 

 mens. Color same as in Stage IV, about the only difference between this stage and 

 Stage IV being the enlarged size. Point of prothoracic shield extending over the 

 first segment of the abdomen and wing pads extending to posterior part of second 

 abdominal segment. 



LIFE HISTORY AND HABITS 



The observations on the three-cornered alfalfa hopper have been car- 

 ried through two years and parts of two others at Tempe, Ariz., and 

 through one entire year at Greenwood, Miss. The results, therefore, have 

 been secured under widely differing conditions, the former place being in 

 a hot, semiarid country with an annual rainfall of about 8 inches, while 

 the latter is in a warm, humid country with an average aimual rainfall of 

 nearly 50 inches. 



In the Salt River Valley of Arizona much difficulty was experienced in 

 securing Itfe-history records during the months of June, July, and August, 

 because of the excessive heat. In order to have the specimens under 

 close observation, it was, of course, necessary to confine them in cages 

 under more or less artificial conditions, and under such conditions the 

 death rate among nymphs was very high. The combined lengths of the 

 egg and nymphal stages under Arizona conditions varied with the tem- 

 perature, being from 35 to 114 days, with an average of about 50 days 

 for all conditions. In Mississippi Mr. Gibson found that a much shorter 

 period was required. Here the variation, as shown by observations on 

 a much smaller number of specimens, was from 26 to 37 days. Rec- 

 ords of a larger number of specimens would doubtless have given a wider 

 variation. 



EGG STAGE 



In Arizona the egg stage varies from a minimum of 12 days to a maxi- 

 mum of 41 days, this variation depending upon the prevailing tempera- 

 ture. The average for all records is 22 days. As may be seen in Table 

 II, during an average mean temperature of 59° F. the time required for 

 incubation varied from 33 to 43 days. At a mean temperature of 63° 

 the variation was from 23 to 30 days, while with a mean temperature of 

 about 85° the eggs hatched in a period ranging from 12 to 17 days. 



