164 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



Generous fertilization will aid the plants in overcoming 

 injury very considerably. Dr. J. B. Smith advises " the applica- 

 tion of all the necessary potash in the form of kainit, put on as 

 a top-dressing after the field is prepared for planting," and says: 

 "Fall plowing and kainit as a top-dressing in spring will, I feel 

 convinced, destroy by all odds the greater proportion of the web- 

 worms that infest the sod, and would also destroy or lessen many 

 other pests which trouble corn during the early part of its life." 



The Corn -root Aphis * 



Where patches of corn become dwarfed, the leaves becoming 

 yellow and red, with a general lack of vigor, the grower may well 

 be suspicious of the presence of the Corn-root aphis. These 

 little aphides, which cluster on the roots of corn, are a bluish- 

 green color, with a white waxy bloom, and of the form shown in 

 Fig. 120. Two short, slender tubes project from the posterior 

 part of the abdomen which are commonly called honey-tubes, 

 because they were formerly supposed to give out the honey-dew, 

 which is so relished by the ants which tend the aphides to secure 

 it. The winged female has a black head and brownish-black 

 thorax, with pale green abdomen bearing three of four blackish 

 marginal spots and small dark specks over the surface. The 

 antennae are dark and the legs blackish. 



The corn-root aphis occurs throughout the principal corn- 

 growing States, but has been most destructive where corn is 

 most extensively grown and is often planted year after year 

 on the same land. Dr. Forbes, to whom we are indebted for 

 most of our knowledge of this pest.f has observed fields of corn 

 in Illinois planted in corn for the second season totally ruined 

 by the root-aphis. Broom-corn and sorghum are the only other 

 cultivated crops which have been injured, but the list of food 

 plants includes smartweed, purslane, ragweed, foxtail, and crab- 



* Aphis maidi-radicis Forbes. Family Aphididce. 



t S. A. Forbes, 17th, 18th, and 25th Reports of the State Entomologist 

 of Illinois; Bulletin 60, Bureau of Entomology, U. S. Dept. Agr., p. 29; 

 Bulletins 104 and 130, Illinois Agr. Exp. Sta. See also J. J. Davis, Bulletin 

 12, Part VIII, Technical Series, Bureau of Entomology,, U. S. Dept. Agr., 

 and 7 M. Webster, Circular 86, Bureau of Entomology, U. S. Dept. Agr. 



