CLOVER AND ALFALFA SEED CHALCIS-FLY. 



13 



to tho adult stage to be from 26 days to 24 months, and, in a few 

 cases, to carry the individuals through two winters before the adult 

 stage is reached. 



RELATIVE INFESTATION THROUGHOUT THE SEASON. 



During the season of 1915 newly formed alfalfa seed pods were 

 taken at Bard, Calif., at intervals of about one week, and examined 

 for infestation by the seed chalcis-fly. It was found that the seed 

 pods taken as early as April 21 showed 39 per cent of the seeds to be 

 infested. On May 8, as many as 52 per cent showed infestation by 

 the chalcis-fly. This was undoubtedly due to the increased emer- 

 gence of the chalcis-flj^ The period from the middle of May to the 

 middle of Jul}^, at which time the pods were forming in great 





Alfalfa along fence lines, afite/t 

 hanks and Was-fe areas 



Alfalfa seed fields 



Mo. 



^9^' 



Larvae 



Pupae 



Adults 



E33S 



L arvae 



Pupae 



Adults 



reeding 



Resting 



Feeding 



Resting 



fih. 







^Ma' 











m 







Mar. 







=r~ 



=s^ 









r 





^ 



Apr^ 



■m. 



\. 



^ 









z 



■ 



Jun. 

 Jul 



Aug. 

 Sep. 

 Oct 



AW. 



_^_ 



L 



^^ 



*■ 









^ 



Z^ 



z 



=^ 



=- 



=^ 







^■^ 





^^^ 



• 





» 







^^^ 



^ 







^^^^ 



M 



ss^ — 



— ^ 





Sir 





n 



nz^ 



.^^_. 



^^ 



^S^ 



^ 



^^ 







^~ 



" 



^~ 



Dec. 



'' 



v- 



m^rn^ 



" 



^ 







~ 







Ja». 

















Z 







Feb. 

















Z 







Fig. 2. — Diagram showing comparative abundance of 

 6r(s during the different months 



the stages of Bruohophagus fune- 

 of the year. 



abundance, showed the infestation dropping to an average of 28 

 per cent. 



The average infestation for the period from the middle of July 

 to the end of September increased to 49.5 per cent. This was un- 

 doubtedly due to the increased number of the chalcis-flies and to the 

 rapid decrease in the seed pods caused by the cutting of alfalfa on 

 many of the seed fields. 



By October all the seed fields had been harvested, and the chalcis- 

 flies were forced to breed in the gi'een pods still forming along the 

 edges of the fields. Seed pods collected on October 12 showed 85 

 per cent of the seeds to be infested. 



Figure 2 shows the comparative abundance of the stages of B. 

 funebris during the different months of the year. 



It will be noted by the chart that eggs of B. funebris are found 

 earlier along fence lines than in the seed field. This is due to the 



