Rural School Leaflet 1183 



this grub changed to a pupa and twenty-three days later, on August 

 31, it changed to a beetle. If it had been left alone the beetle would 

 probably have remained in the ground until the next spring, in 1896, 

 thus making nearly three years from the egg to the beetle. It is 

 supposed, from this record and from many other observations made by 

 different persons at different times, that most of the May beetles in 

 our northern States take three years for their life history. It has only 

 recently been shown by an investigator that one of the less common 

 and less injurious species passes its life history in two years. 



The grubs grow slowly while in the soil. During the first summer they 

 are small and cause very little injury. In the second summer they are 

 larger and destroy more, and in the third summer they have become nearly 

 full-grown. Then they are ravenous and demand large quantities of food. 

 It is during this last summer in the ground that they do the most injury. 



Appearance and habits of white-grubs. — White-grubs vary in size 

 from about one inch to over an inch and a quarter in length. They have 

 a brownish head, with a pair of strong, black, horny jaws. Just back 

 of the head are six strong legs, the end of each one of which is flattened 

 somewhat like the foot of a mole. Probably the feet are used for digging 

 burrows through the soil. 



The body of a white-grub lies in a half-curled position; in fact, it is 

 impossible to straighten the body and make it remain straight. The 

 rear end of the body is blunt, rounded, and often darker in color than 

 the rest of the abdomen. 



White-grubs are sluggish creatures, and it is belived that they do not 

 move far from the place in which they were hatched from the eggs. It 

 is true that they move through the soil to some extent, for an infested 

 place in a lawn or field will gradually enlarge in all directions. This 

 shows that the grubs move slowly outward in all directions from the place 

 at which they started, gradually devouring the roots of the plants as they 

 go; but they are not known to migrate from field to field. During 

 summer the grubs keep near the surface of the ground, but in the fall 

 they go down out of the way of the sudden changes of thawing and freezing. 

 In the spring, after the frost is out of the ground, they return near to 

 the surface again. 



The number of white-grubs sometimes present in a field is really 

 amazing. Doctor Forbes and his assistants showed that in a badly infested 

 ten-acre field of corn in Illinois there were, on the average, more than thirty- 

 four grubs to each hill of corn, or about three hundred pounds of grubs 

 to the acre. This is not an uncommon number to be found in the soil. 



Crops destroyed. — We have already alluded to the preference of white- 

 grubs for the roots of grasses. We once saw the roots of the grass of 



