White Grubs 



Sugar beets, potatoes and corn are among the field crops most seriously 

 damaged. Garden truck and strawberries often suffer heavily, also. 



In the case of potatoes and sugar beets deep pits are eaten into the 

 tubers and roots. If sugar beets are damaged when the plants are small 

 the root is eaten off two or three inches below the surface of the ground. 

 The plant, of course, wilts. If it is pulled the tip of the root at the point 

 where it is eaten off will be dark in color, sometimes almost black. Wire- 

 worm injury is so similar to this that the two are easily confused. Later 

 in the season when the beets have attained some size they may not be 

 entirely eaten off but portions of their surface will be eaten away. Beets 

 attacked at this time of the year usually wilt, especially in the heat of 

 the day. Such beets are easily pulled because the grubs have destroyed 

 most of the smaller roots. When removed from the soil, the surface 

 will be found pitted, the pits being dark in color and rough on the surface. 



The adults (beetles) of many of the injurious June bugs feed upon 

 the leaves of various trees, mainly cottonwoods and willows in the beet- 

 growing areas covered by this Bulletin. Injury by white grubs has been 

 noted only in river bottoms where natural sod and the trees mentioned 

 above are both common. Crops following sod or crops in which 

 much grass was allowed to grow are most apt to be injured. 



METHOD OF CONTROL 



There is no known method by which an infested field can be freed 

 of white grubs without injury to growing crops. However, measures can 

 be taken which will reduce the injury or prevent future losses. 



Pasturing with Hogs 



When practical, pasturing with hogs will rid land of grubs. There 

 is one drawback to this method, however. This lies in the fact that the 

 giant thorn-headed worm, an internal parasite of swine, passes one stage 

 of its life in certain white grubs. Hogs eating these grubs become in- 

 fested and grubs eating the excrement of such animals become infested 

 in turn. If no hogs have been pastured on land for at least three years, 

 grubs in it will not contain this parasite, and hogs pastured on such land 

 will not become infested. 



Rotation 



White grub losses can be reduced by practicing a proper system of 

 rotation. Since the beetles usually deposit their eggs in fields of grass or 

 small grain, sugar beets, potatoes or corn should not follow these crops in 

 localities where grubs occur unless the ground is known to be free from 

 them. Alfalfa, clover, buckwheat, peas and small grain are not damaged 

 to the same degree as the crops mentioned above. 



Plowing 



Fall plowing, if done early, is a great help in destroying this pest. 

 As the grubs burrow deep into the soil as cold weather comes on, to be 

 effective, fall plowing must be done not later than October. Fall plow- 

 ing is much more effective if followed by the disc or harrow. Plowing 

 infested land in July or August will destroy many beetles, as the change 

 from pupa to adult takes place about this time and the newly trans- 

 formed beetles are easily killed. 



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