NATURAL ENEMIES. 



While Doctor Riley found the larva of one of the common soldier 

 beetles, probably Telephorus hilineatus Say, attacking the larvae of the 

 borer, and although it probably has other enemies, both among 

 insects and birds, these have so far proven of little economic impor- 

 tance. 



PREVENTIVE MEASURES. 



The only preventive measure yet tried that gives any promise of 

 success is summer fallowing as soon as the hay crop is removed. 



At this time the young are in an immature state and, if deprived 

 of food, must perish. They can not migrate from one clover root to 

 another, and, if the meadow is now broken up, throwing the roots 

 up to the hot sun and winds, these wither and dry, thus no longer 

 supplying the necessary sustenance, at this time so imperative to the 

 life of the larvae, and they perish. Thus an invasion of a new field 

 from an old one may be prevented. But if the fallowing be delayed, 

 even for a few weeks, the larvse w^ill then have for the most part passed 

 into the pupal stage, during which no food is required, and plowing can 

 have little or no effect upon them. This measure, together with the 

 practice of allowing clover fields to stand only two years, would soon 

 reduce the pest to subjugation in any community. No trouble from 

 its work seems to occur in pastures. Once brought under control, 

 it would seem that a system of rotation that involves mowing for 

 hay and seed the first year, and pasturing and then breaking up the 

 ground the following year, if generally followed in a community, 

 would suffice to keep the pest in subjection. Extermination is not 

 possible. 



Approved : 



James Wilson, 



Secretary of Agriculture. 

 Washington, D. C, January 12, 1910. 



[Cir. 119] 



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