20 INJURIOUS INSECTS OF KANSAS. 



OORN-ROOT LOUSE. 



{Aphis maidi-radicis Forbes; Order, Hemiptera.) • 



Diagnosis. — Corn plants grow slowly, or not at all ; appear yel- 

 low and sickly. Examination of the roots reveals small bluish- 

 green particles, masses of lice. 



Description and Life-history. — This minute insect, one of the 

 plant-lice, has until lately been believed to be a root form of the 

 Corn-louse which lives above ground on the leaves and stalks. 



Fig. 10. Corn-hoot Louse; a, winged female; ft, wingless female (stem-mother); 

 c, wingless, egg-laying female; d, pupa. 



Professor Forbes, of Illinois, has clearly shown the distinctiveness 

 of the two forms. With proper magnification by a microscope, 

 the Corn-root Louse appears as a wingless, soft-bodied, bluish- 

 green, sub-ovoid insect ; or it may have four transparent mem- 

 branous wings. 



The louse passes the winter in the egg state in the nests of cer- 

 tain small, brown ants {Lasius hrimneus var. alienus), which ants 

 are always found associated with the lice. The young lice hatch 

 in April, and begin to feed upon the roots of young smart-weed 

 plants {Polygonum); and later upon the common crab-grass 

 (Setaria). As soon, however, as the corn is planted and begins 

 growing, the lice go to the corn roots, and there live. In October 

 the eggs for next year's generation are laid. 



Remedies. — As the young lice are usually hatched before the 

 corn is planted, and have to live on other plant roots, as smart- 

 weed and crab-grass, any means for keeping down the spi'outing 

 herbage in the fields in early spring will tend to starve the young 

 lice. It has been found that the young lice cannot live more than 

 five days without food. "Any treatment of the field the preced- 

 ing summer or fall which should diminish the number of seeds of 



