INSECTS INJURIOUS TO CORN. 



259 



small per cent of the eggs of the aphids, or the aphids themselves, should 

 they hatch, and the great bulk of the injury that would have followed is 

 thereby prevented. Then again, this frequent harrowing will prevent 

 the development of the smart-weed and fox-tail or pigeon grass, which 

 will also do away with the food plants, on the roots of which the little red 

 ants will place the aphids if they can find the aphids and the plants to do 

 so. Good results will follow by delaying the planting of corn about 

 two weeks later than one would normally put it in the ground, and during 

 these two weeks harrow the field with the disk harrow at least twice. 



NORTHERN CORN ROOT-WORM. 



Diabrotica longicornis, Say. 



The northern corn root-worm sometimes causes several million dol- 

 lars' damage to corn by injudng the roots of the same, but its work is 

 often largely mistaken for that of the wireworms and other root-feeding 

 insects. The wireworms, however, do cause the greatest loss to the corn 

 crop by root injury. Frequently corn in localities, especially in high, 

 dry places, will not grow as fast 

 as the corn in a neighboring area, 

 and frequently such corn will be 

 only six inches or a foot in height, 

 when all about this infested area 

 it will be four or five feet high. 

 It also frequently happens that 

 corn in infested localities of a 

 field will fail to make ears at all 

 or the ears will consist largely of 

 nubbins. Then, again, corn in cer- 

 tain areas will fall down by an or- 

 dinary brisk rain or wind and re- 

 main there, failing to regain its 

 upright position. 



With these symptoms one ^ig 1 8.— Northern corn Root-Worm. Dl- 

 ■' ^ aorottca longxcorms. Adult Beetle ; enlargea 



can mistrust the presence of the ^^" diameters. 



northern corn root-wonn, but as the wireworm causes a similar effect, 

 one can only readily know the presence of this northern corn root-worm 

 by pulling up a few hills of corn and examining the roots. The wire- 

 worms eat off the roots and mine more or less through the lower part 

 of the stalk, or, rather, the base of the roots, while the northern corn 

 root-worm mines inside of the root itself and does not, at least as a rule, 

 enter the base of the roots or the stalk at all. 







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