INSECT PESTS 175 



slowly, and requiring two years or more 

 to become full size. Larvae of proper age 

 and size change to pupae in midsummer 

 and the adult stage is reached by Septem- 

 ber, but the beetles remain in the earthen 

 cells made by the larvae until the following 

 spring. Thus it is seen that the life cycle 

 of white grubs is similar to that of wire- 

 worms. Larvae of different ages are pres- 

 ent in the soil at all times in the year; 

 hence injury caused by them may be con- 

 tinuous. 



