STRAWBERRY INSECTS 



396 



age depth of about three inches. At the approach of cold 

 weather they burrow deeper and hibernate at an average depth 

 of ten inches. A few, however, may remain near the surface, 

 while others may descend to a depth of two feet or more. They 

 return to the roots in early spring and complete their growth by 

 June or July. The grub then constructs an oval earthen cell 

 (Fig. 339) a few inches below the surface within which it soon 

 transforms to a delicate helpless pupa. The insect remains in 

 this condition till August or September and then transforms to 



Fi(i. 340. — Two .species of .June-beetles, 

 the adults of the white grub, Lachnosterna 

 ilicis and L. hirticula. 



Fi(i. 



.'Ml. — A .June-beetle, 

 Lachnosterna fusca. 



the adult or beetle. As a rule, these beetles remain in the pupal 

 chamber till the following May or June. It is thus seen that 

 while the grubs mature in about two years the whole Ufe-cycle 

 from egg to egg requires three years. 



Treatment. 



White grubs are most abundant in land which has been for 

 some time in sod or has been occupied by old strawberry beds. 

 Strawberries should never be planted on badly infested land; 

 OA\ing to lack of other food, the grubs concentrate on the straw- 

 berry roots and soon kill the plants. Clover is not attacked to 

 any great extent by white grubs, and may be used to advantage 

 as an intervening crop between sod and strawberries. Much 



