228 



INSECTS AFFECTING WHEAT. 



plants of the grass family. It obtains its food by in- 

 serting appointed beak into the leaf or stem and 

 sucking out the sap. As the wheat gets ripe it mi- 

 grates to the more succulent oats, and when these 

 ripen goes to various grasses. It brings forth living 

 } 7 oung, and its rate of multiplication is very great, it 

 being estimated that a single 

 louse in spring may become 

 the ancestor of millions be- 

 fore autumn. The true sexed 

 forms have not yet been 

 found. The wingless vivipa- 

 rous female is represented, 

 greatly magnified, at Fig. 

 121. The injury of these in- 

 sects is chiefly manifested by 



Fig. 121. Grain Aphis: wing- 

 less female. Magnified. 



the shriveling of the grain in 



infested fields. 



Fortunately this insect has many natural enemies 

 with which to contend. Chief among these are little 

 four-winged parasitic flies, and various species of 

 lady-beetles. These natural enemies are undoubt- 

 edly the means of preventing this pest from over- 

 running grainfields every year. 



Remedies. — As yet no practical artificial remedy 

 for the Grain Aphis is known. Kerosene emulsion 

 will destroy them, but the difficulty of reaching them 

 with it when they occur on the under surface of the 

 leaf, makes the remedy hardly practical. We must 

 ordinarily rely upon the weather and its various 

 natural enemies to hold it in check. 



