CLOVER AND ALFALFA SEED CHALCIS-FLY. 15- 



such a depth that the emerging luhilts are unable to reach the sur- 

 face, because tlie sliglitest covering of moist soil Avill cause many 

 of the infested seeds to mokl, and prevent development of the pupal 

 or adult stages. 



The necessary cultivation can be accomplished by the use of an 

 alfalfa cultivator, spring-tooth harrow, or a disk. Care should be 

 taken that the surface of the field is left smooth, to facilitate close 

 cutting, as well as to prevent clods and gravel from being taken up 

 with the seed when the seed crop is harvested. 



IRRIGATION OF ALFALFA SEED FIELDS. 



Whenever possible, the alfalfa seed grower should do most of his*, 

 irrigating in early spring, or before the seed crop is grown. Where 

 this can be practiced, two important points may be gained. First,, 

 the tender, rank growth of alfalfa usually following irrigation will 

 be removed as an early fodder crop, and a steady gi-owth of more 

 substantial stems will take its place to produce the seed crop. Second, 

 irrigation of a seed field stimulates the emergence of the chalcis- 

 flies which remain within the infested seeds upon the ground. The 

 humidity of the atmosphere! over an irrigated field accelerates the 

 emergence of this pest from seeds of the newly forming crop, which 

 would otherwise become sufficiently dry to force many of the larva3 

 into a resting period. 



It has been supposed by farmers that flooding the seed fields after 

 the first crop of alfalfa has been removed would destroy the larva? 

 of the chalcis-fly present in alfalfa seeds upon the ground. The 

 writer has found that soaking infested seed in water for four or five 

 days is not sufficient to kill the larvae resting within the seeds. This 

 would render any attempt at their destruction by irrigation im- 

 practical. 



CUTTING EARLY PLANTS ON WASTE AREAS. 



The fence lines, ditch banks, and other waste areas where volun- 

 teer alfalfa can be found, are among the great sources of infestation. 

 It has been found that the chalcis-fly frequently passes through one 

 or two generations on this volunteer alfalfa before the seed fields 

 are advanced to the point where infestation takes place. Every 

 farmer, therefore, in an alfalfa seed-growing district should cut all of 

 the standing alfalfa along the fences and waste areas at the time a 

 hay crop is cut before he grows a seed crop. Alfalfa seed pods 

 should not be allowed to develop anywhere around the field until the 

 plants of the regular seed crop have begun to form pods. 



CAREFUL CUTTING OF HAY CROPS. 



It is of the greatest importance that special care should be exer- 

 cised in cutting alfalfa or red clover before the seed crop is grown. 



