INSECTS INJURIOUS TO CORN 



165 



grasses, and many other weeds and grasses which spring up in 

 the corn-field. In South Carolina Professor A. F. Conradi has 

 found it injuring cotton. 



If the nests of the small brown ant * so common in corn-fields 

 infested with the root-aphis, be broken open during the winter, 

 many of the little black aphis eggs, which have been carefully 

 stored by the ants, will be found. They are a glossy black color, 



FIG. 120. The corn root-aphis (Aphis maidi-radicis Forbes): at left, ovip- 

 arous female; a, hind tibia, showing sensoria; at right, male: a, antenna 

 much enlarged. (After Forbes.) 



oval in shape, and will sometimes be found in small piles in 

 the chambers of the ants' nests. On warm days the ants bring 

 them up to the warmer surface soil and in cold weather carry 

 them far down into the unfrozen earth. With the appearance 

 of young smartweed and foxtail-grass in April and May the eggs 

 commence to hatch. The ants at once lay bare the roots of 

 these plants and carry their young wards to them, where large 

 colonies soon become established. If the field is not planted in 



* Lasius niger Linn. var. americanus Emery. See Forbes, Bulletin 131, 

 Illinois Agr. Exp. Sta. 



