14 BULLETIlSr 812, U. S. DEPAKTMENT OF AGRICXJLTTJRE. 



fact that isolated plants on waste areas form the earliest pods, and 

 the seed fields are cut for hay before the seed crop is grown. A. 

 sudden scarcity of eggs, feeding larvae, and pupse is seen in the field 

 in October, which is due to the harvesting of the latest seed crops. 

 Eesting larvae continue to remain on the field throughout the winter 

 in remaining seed pods, but are much more abundant along fence 

 lines. Spring irrigation of seed fields hastens emergence of adults,, 

 and this results in the absence of resting larvae and pupae on most, 

 fields during the month of May. 



PARTHENOGENESIS. 



The parthenogenetic habit is well established in the females of 

 this species. Female adults, reared from pupae which were com- 

 pletely isolated, were placed in cages for oviposition into green 

 alfalfa seed pods. All precautions were taken against earlier in- 

 festation of the green seeds. These virgin females oviposited freely,, 

 and their progeny was reared in breeding cag^. The largest num- 

 ber of offspring from a single female observed by the writer was 20,, 

 and all of the progeny of these virgin females prpved to be males. 



CONTROL METHODS. 



The practical methods of controlling the chalcis-fly in the alfalfa 

 and clov^ seed fields are mostly cultural methods. It can not be 

 hoped to eradicate this pest from any seed-producing locality; but 

 with the proper methods effectively applied thousands of dollars 

 can be saved annually to the different seed-growing districts. Be- 

 cause of the rapid dispersion of the adults of this species it is of 

 vital importance that control methods should be taken up by com- 

 munity action rather than by the individual. 



BURNING OVER OF FENCE LINES. 



Everywhere in the alfalfa and red clover seed-growing districts 

 one; will find large quantities of standing plants along the fence 

 lines and waste areas bearing the seeds infested by hibernating larvae. 

 Many hibernating larvae of the chalcis-fly can be destroyed in the 

 fall of the year by burning over such areas, thereby greatly lessen- 

 ing the abundant emergence of adults in early spring. It has 

 been found that live stock can not be depended upon to rid the fence 

 lines of standing alfalfa in the wintefr unless there is a great short- 

 age of forage. 



WINTER CULTIVATION. 



The cultivation of alfalfa seed fields during the winter is of much 

 value in covering the infested alfalfa seeds containing hibernating 

 larvae. It is not necessary that infested seeds should be covered to 



