492 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



control. One species, at least, passes the winter in the corn 

 stubble, and can be killed by burning the stubble. They will 

 all be less injurious in fields where root crops are rotated with 

 corn or wheat crops. 



The Corn -root Aphis (Aphis maidi-radicis). Sometimes the 

 corn roots are badly infested with little greenish plant-lice 

 that suck the sap from the plant. The life-history of this 

 insect is especially interesting as it shows the close relation that 

 ants and plant-lice sometimes bear to each other. In the fall 

 the little brown field ants, Lasius brunneus, gather the eggs 

 that have been laid by the aphids in the ground, and store them 

 in their nests. Here they are cared for until they begin to hatch 

 in the following spring. The ants then carry the young plant- 

 lice to the roots of grasses or weeds that grow in the cornfield 

 and carefully tend them there, moving them to new plants 

 when the old ones become overcrowded. When the corn is 

 planted many of the aphids are transferred to the roots of the 

 corn, and, as they increase in numbers very rapidly, much 

 damage may be done in some fields. Because the ants tend 

 them with such care and receive in return the honey-dew 

 that is secreted by them these aphids are often called " ant- 



cows. " 



If grasses or weeds are not allowed to grow in the field during 

 the early spring most of the aphids will starve before the corn 

 sprouts. 



The Corn Ear-worm, which frequently does much damage 

 in the field, has been discussed on page 486. 



WHEAT 



Chinch-bugs (Blissus leucopterus). The adult chinch-bugs 

 are only about one-fifth of an inch long. The body is dark- 

 colored, and the whitish wings, which lie folded over the back, 

 are each marked by a dark triangular spot. The very young, 

 often called "red-bugs," have no wings, but these gradually 

 develop as the insect passes through its successive molts. 

 Because of their habit of assembling in such great numbers on 

 the stems of wheat, corn and many other field crops, the 

 chinch-bugs are often the worst pest the farmer has to 



