CORN PESTS AND DISEASES 



275 



that they were the source of the abundant excretion 

 upon which the ant attendants of the lice eagerly feed. 

 The grass louse, on the other hand, is white in color, 

 with a blackish head and other blackish markings, but 

 without any tint of green ; it has no traces of honey 

 tubes, their place being taken by two minute openings 

 in the corresponding segment of the body, each sur- 

 rounded by a delicate brownish rim. 



From our present knowledge of these pests, there 

 seem to be at least four methods to attack them. Pro- 

 fessor Forbes, in summing up the results of work done 

 in Illinois, thinks farmers may (1) try the effect of a 

 change of crop after any notable plant louse injury to 

 corn, in the expectation that corn planted on ground 

 which contains no plant louse eggs will become so 

 slightly or so slowly infested, if at all, that no harm 

 need be anticipated. (2) The application of fertilizers 

 and other materials made to the young corn hill in 

 spring in the hope of killing the lice outright or 

 of supporting the plant against their attack at a time 

 when this is likely to be most injurious. (3) Since 

 the small brown ant cares for the eggs in winter 

 and spring, it is thought the lice can be lessened by 

 disturbing the nests or breaking them up and dis- 

 persing their contents in late fall or winter, so 

 that their stores of aphis eggs cannot be recovered 

 by them, and thus left to perish. (4) Taking 

 account of the early hatching of the eggs in spring, 

 several days, as a rule, before the usual time for 

 planting corn, and the dependence of the young 

 lice for food at that time on sprouting weeds in the 

 field, especially smartweed and pigeon grass, the 

 ground should be handled in such a manner that there 

 shall be no sufficient start of vegetation to keep the 

 lice alive. Delay somewhat, 'A necessary, the planting 

 of the field to corn. There can be no doubt that a 



