INSECT ENEMIES OF WESTERN FORESTS 



25 



The large, shining, brown "June bugs" (fig. 10) often lay their 

 eggs in grassy places or where the ground vegetation is heavy. In 

 the North, where the life cycle is 3 or more years in length, the small 

 white grubs feed during the first summer on organic material and 

 on small rootlets near the surface of the soil. As cold weather ap- 

 proaches they burrow more deeply into the soil and hibernate. The 

 second season the grubs are larger and do their greatest damage to 

 the roots of seedlings and small trees. They again hibernate over the 

 second winter and again feed during the following spring. The full- 

 grown grubs are white, thick-bodied, with dark-brown heads and 

 three pairs of well-developed legs. They always lie in a tightly 

 curled position and are familiar ob- 

 jects to everyone who has dug for fish 

 bait. In midsummer of usually the 

 third season they reach full growth, 

 transform to the pupal stage within a 

 cell in the ground, and emerge the fol- 

 lowing spring as full-grown beetles. 

 In the Southern States the cycle may 

 be completed in 2 years, or possibly 

 less, while in the North and in Canada 

 it may take 3, 4, or even 5 years. 



The prevention of white grub dam- 

 age can be accomplished to a great 

 extent through modification of cul- 

 tural operations. New ground that is 

 to be used for nursery purposes should 

 be put under cultivation for 2 or 3 

 years to allow for the emergence of 

 beetles already in the ground and to 

 avoid new egg laying. 



If transplant beds are cultivated 

 frequently in the seasons when they 

 are lying fallow, and these periods of 

 resting are interspersed between the 

 period of use, the damage by white 

 grubs will usually be comparatively 

 light. Infestation in seedbeds is likely to give the most trouble, since 

 the dense growth produces a favorable condition for egg laying, and 

 the beds cannot be cultivated until the seedlings are taken up. Beds 

 can be protected by covering them with a i/4-inch mesh wire screen 

 during the egg-laying period. If the beds become infested, the young 

 seedlings should be dug the second spring to avoid heavy damage. 

 Clean cultivation, screening of seedbeds, and rotation of transplant 

 beds are first steps in holding white grub damage to a minimum, but 

 even these are not ahvays successful. 



Seedbeds which must be repeatedly used may become heavily in- 

 fested. Kecent experiments have indicated that the grubs can be 

 killed by the use of 50-percent miscible carbon disulphide. A satis- 

 factory dosage consists of 1 quart of the miscible carbon disulphide to 

 50 gallons of water and an application of 3 pints of the emulsion to 

 each square foot of soil surface. Care should be taken not to allow 

 any of the solution to come in contact with the leaves of the young 



FiGUEEi 10. — Adult beetle, eggs, and 

 larva or white grub of PolypTvylla 

 crinita Lee. X 2. (Drawings by 

 Edmonston.) 



