WHITE GRUBS 



135 



bed under the previous fall. If the aphids appear early in the 

 spring, spray the strawberry crown with nicotine solution 

 one part to 1000 parts of water. Affected plants intended for 

 shipment should be fumigated for ten minutes with hydrocyanic 

 acid gas, made by using: Potassium cyanide, 1 ounce; sulfuric 

 acid, 2 ounces; water, 4 ounces. This is for every one hundred 

 cubic feet of space. (See page 62.) The deadly nature of this gas 

 should not be overlooked, and precautions must be taken to insure 

 safety. (See also methods of control given under strawberry 

 crown-borer and strawberry crown miner.) 



White Grubs. The larval forms of different species of Lach- 

 nosterna are called June beetles, May beetles, or June "bugs." 

 The larvae are commonly called grub worms. They are un- 

 doubtedly the worst of the pests attacking strawberries. They 

 feed also on potatoes, roots of young evergreens in nurseries, and 

 roots of young apple stock. A strawberry crop following directly 

 after sod is very apt to suffer, since the grubs, deprived of their 

 natural food, turn their attention to cultivated plants. 



Life History. Ordinarily, eggs are laid by the beetles in grass 

 or sod lands some time in May or June. Grubs hatch in July and 

 begin feeding on rootlets. They grow to less than one-half inch 

 during the first season, retiring, so it is claimed, below the 

 frost line when winter sets in. This statement is questionable 

 where northern latitudes are concerned. The second season they 

 continue feeding and grow to about one inch in length. Growth 

 is completed the third season in midsummer, and the pupal stage 

 is passed in a cell a few inches below the surface of the ground, the 

 pupa gradually changing to an adult, and remaining below the 

 ground until the following May, when it emerges. 



Control. Where these white grubs are actually hi a strawberry 

 field, there is nothing to do but dig them out when a plant shows 

 injury. If it is necessary to use sod land for strawberries, such 

 land should be plowed hi early September. This process tends to 

 kill a portion of the brood ready to transform, but will not kill the 

 younger grubs while hi the ground. A rotation of crops is desirable, 

 and the sod should be followed with some crop other than straw- 

 berries for two years or more. Clover is said to be ideal for this 

 purpose, as these insects do not attack it severely. Cropping straw- 

 berries for one year only is manifestly another way of avoiding 

 injury. Where hogs can be used in infected land, they are a great 

 help. Since the most severe injury from white grubs is periodic, 



