INJURIOUS INSECTS 



135 



given to any onions that may be found infested at harvest 



time. When onion land becomes badly infested with this 



pest, crop rotation should be practiced and no onions should 



be raised near it for a year or two. When beans, corn, and 



peas are affected the seed should be treated with a very 



thin coating of coal tar and afterwards rolled in plaster or 



other dust. The coal tar may be applied as follows: 



Spread the grain out in a warm room on the floor about 



six inches deep and wet 



it with warm water; 



sprinkle on a very little 



warm coal tar (about one 



tablespoonf ul to one-half 



bushel) until each grain 



is coated ; then roll it in 



plaster to dry it off. If 



this is carefully done 



the grains will not stick 



together and may be 



planted by any planter. 



This treatment also prevents crows, gophers, and squirrels 



from pulling newly planted corn. 



When it attacks cabbage, cauliflower, and similar 

 plants it may be destroyed by kerosene emulsion, since the 

 maggots work on the stem and roots of the plant near the 

 surface of the ground and such an application would be 

 practicable in this case; while in the case of many other 

 crops, such as onions, beans, etc., it might be quite out of 

 the question on account of the large number of plants that 

 would have to be treated to make it effectual. In the case 

 of cabbage, however, it may be prevented from entering 

 by inserting the plant through a small piece of tarred paper 

 that is allowed to remain flat on the surface of the ground. 



Fig. 50. The common onion maggot in 

 various stages. 



