10 



BULLETIN" 124, U. S. DEPARTMENT OF AGRICULTURE. 



PUPA. 



The pupa (fig. 6) is yellowish green, with a conspicuous row of 

 black dots just within the margin of each wing pad and three black 

 dots on each side of the abdomen. It is free, having no cocoon, and 

 is found, head up, attached closely by the posterior end to an alfalfa 

 stalk or other support, with the anterior end hang- 

 ing loosely in a threadlike swing which is joined to 

 the same support. 



LIFE HISTORY AND HABITS. 



The complete life cycle for this insect averages 

 about 38 days for all generations, the minimum 

 length being about 26 days for the third brood and 

 the maximum 64 days for the first brood. (See 

 Table III.) The time occupied by the different 

 stages is as follows: Egg, 6 days; larva, 24 days; 

 pupa, 7 days, and a resting and feeding period of 

 1 day following emergence of adults during which 

 copulation takes place. Males usually complete the 

 developmental period several days sooner than the 

 females, and thus pass a longer period between 

 emergence and copulation. Mr. W. H. Larrimer, working at Nash- 

 ville, Tenn., made some interesting records on the life-cycle periods, 

 as shown in Table I. It will be noted that these records were all 

 made during the months of June and July and correspond with the 

 tables for Arizona showing records made during weather of medium 

 temperature. 



Table I. — Rearing records for the alfalfa caterpillar, Nashville, Tenn., 1913. 



Fig. 6. — The alfalfa 

 caterpillar : Chrys- 

 alis, or pupa. 

 (Author's illustra- 

 tion.) 



Egg laid. 



Egg 



hatched. 



Egg 

 stage. 



Larva 

 pupated. 



Larval 

 stage. 



Adult 

 emerged. 



Pupal 

 stage. 



Food plant. 









Days. 





Bays. 





Days. 





June 



4i 



June 7 



3 



June 26 



19 



Julv 2 



16 



Medicago sativa. 





41 



7 



3 



July 1 



24 



8 



7 



Do. 





4 



7 



3 



3 



26 



10 



7 



Do. 





27 



30 



3 



16 



16 



23 



7 



Do. 





27 



30 



3 



16 



16 



23 



7 



Do. 



July 



21 



July 5 



3 



22 



17 



29 



7 



Do. 





21 



5 



3 



23 



18 



29 



6 



Do. 





2i 



5 



3 



28 



23 



Aug. 1 



5 



Do. 





2i 







3 



30 



25 



6 



7 



Do. 





16' 



19 



3 



Aug. 2 



14 



8 



6 



Trifolium hvbridum. 





27 



30 



3 



13 



14 



20 



7 



Trifolium repens. 





27 



30 



3 



14 



15 



21 



6 



Do. 





27 



30 



3 



11 



12 



17 



6 



Vieia sativa. 





27 



30 



3 



12 



13 



17 



5 



Do. 





27 



30 



3 



11 



12 



17 



6 



Do. 





27 



30 



3 



15 



16 



21 



6 



Pisum sativum. 





27 



30 



3 



15 



21 



21 



6 



Glycine hispida. 





1 



4 



3 



July 28 



24 



" 



6 



Trifolium pratense. 



1 Reared under same conditions of light, moisture, temperature, and food supply. 



Days. 



Average length of egg stage 3 



Average length of larval stage 18 



Average length of pupal stage , 6 J 



