INSECTS INJURIOUS TO CLOVER AND ALFALFA 205 



hardened. "Even when the direct injury is confined to a portion 

 of the clover-head, the entire head is ruined, for it at length dries 

 up and loses the rest of the florets, leaving only the dead and 

 brown receptacle. Less conspicuous, though not inconsiderable, 

 is the injury at the crown of the plant, done chiefly in September 

 and October, by caterpillars of the same species feeding upon the 

 leaves." Folsom. The total injury varies greatly, but not infre- 

 quently 20 per cent of the heads are infested, and in Iowa infesta- 

 tion has sometimes been exceedingly severe. In any event, every 

 head destroyed means the loss of more than one hundred seeds. 



The larvae become full grown in four to five weeks. The full 

 grown caterpillar is about one-third inch long and varies in color 

 from dirty-white tinged with green to orange, according to the 

 food. The larva spins an oval white silken cocoon, two-fifths 

 inch long, either in the head or at the surface of the ground, 

 which is more or less covered with bits of excrement and floral 

 tissue. The pupa is one-fifth inch long, brown, with the thorax 

 and wing-cases darker, and with two transverse rows of teeth 

 on the back of the abdominal segments except the last, which 

 bears six stout blackish hooks at the tip. The pupal stage lasts 

 two to three weeks and a second generation of moths emerges 

 about the third week of July (in central Illinois). The life cycle 

 is repeated in the same manner and a third generation of moths 

 appears about September 1st. The larvae of the last brood feed 

 either in immature clover-heads or at the crown of the plant. 

 Most of them become full grown and transform into pupae, in 

 which stage they hibernate over winter, while others become full 

 grown, but fail to pupate and hibernate under rubbish. 



Control. Cutting and storing the hay crop early in June as 

 advised for the clover-seed midge will kill the larvae while still 

 in the heads. "The hay should be handled lightly and stacked 

 or stored as soon as possible. Osborn and Gossard * have at- 

 tested the value of this method, and have given these further 

 recommendations: (1) Cut volunteer clover in early June and 

 dispose of the heads speedily; (2) do not allow clover to run for 

 more than two years; (3) sow seed on land remote from old 

 fields; (4) pasture clover in the fall of the first year; (5) plow 



* Osborn and Gossard, Insect Life, Vol. IV, p. 254; Bulletins 14 and 15, 

 Iowa Agr. Exp. Sta.; 22d Report Entomological Society of Ontario, p. 74. 

 Gossard, H. A., Bulletin 19, Iowa Agr. Exp. Sta. 



