FIELD CROP INSECTS 237 



upon the plant roots available and grow slowly, as they 

 require two years or more to become full grown. In the fall 

 they go deeper in the soil and by the first freeze they are 

 from seven to fourteen inches deep. The next year they 

 do much more serious damage and crops are often ruined 

 on sod land which has been planted to corn, strawberries or 

 garden crops. As many as thirty-four grubs have been 

 found in a single hill of corn in an Illinois field in sod the 

 previous year. When the grub is two or three years old it 

 forms a cell from three to ten inches below the surface and 

 there changes to the pupa during midsummer. In August 

 or September the adult beetle wriggles out of the pupal skin 

 but remains in the earthen cell until the following spring, 

 when it emerges fully hardened. Thus three full years are 

 required for the life cycle, although grubs in all stages of 

 development may be found in the soil every year. The 

 adult beetles feed at night upon the foliage of various trees 

 and hide in the soil during the day. Different species have 

 favorite food plants, but all the common decidous shade and 

 forest trees are more or less eaten, maple and poplar par- 

 ticularly. 



A frequent rotation of crops, following sod with some 

 crop not particularly injured by the grubs, will form the most 

 important general means of control, as allowing land to 

 remain in grass for several years furnishes them ideal con- 

 ditions for multiplication. Deep plowing and thorough 

 harrowing in late fall, winter and early spring will break up 

 many of the pupal cells and destroy the tender beetles, both 

 by burying and crushing them and by exposing them to 

 abnormal conditions. Swine will gorge themselves on the 

 grubs on badly infested land and if confined so that they 

 can thoroughly root it over, will effectively clean it of them. 

 Flocks of turkeys or chickens following the plow destroy 



