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THE AMERICAN NATURALIST [Vol. XLIII 



all three taken together if they made their assault on the 

 plant simultaneously. The advantage to both plant and 

 insects of this adjustment of life histories— if one may 

 call it such— is obvious at once. 



That some actual adjustment of larval periods has 

 here been made is rendered somewhat more probable by 

 the fact that a closely related species of Graphops which 

 infests the wild primrose (CEnothera biennis) in southern 

 Illinois, has a life history different from that of the 

 species which breeds in the strawberry— hibernating as 

 an adult, like Typophorus, and not as a larva, like the 

 strawberry species of its own genus. 



Maladjustment or Competitions 

 The corn plant is in greater danger from insect ravage 

 during the first month of its life than at any later time. 

 This is because it offers then a comparatively scanty 

 supply of food, so that a small number of insects may 

 work great destruction; because the single small plant 

 is much more easily killed than a larger one ; and because 

 a larger number of active rival insects infest corn when 

 it is young than at any other time, some of them begin- 

 ning with the recently planted or just sprouting seed. 

 The young roots, the underground part of the stalk, the 

 stalk above ground, and the leaves, both before and after 

 they unfold, are all liable to infestation by several species 

 at the same time. The seed is injured by the wireworms, 

 the seed-maggot, the Sciara larva and the larva of 

 Systena blanda; the roots, by the wireworms, the root- 

 aphis, the corn root-worms, and the white-grubs ; the stalk 

 under ground, by the wireworms, the root-aphis, the 

 southern corn root-worm, and the bill-bugs; the stalk 

 above ground, by the bill-bugs, the cutworms, the web- 

 worms, the stalk-borers, and the army-worm— sometimes 

 by the chinch-bug also; and the leaves, by the bill-bugs, 

 the web-worms, the cutworms, the army-worm and the 

 first generation of the ear-worm. 



This concentration of injury upon the corn when it is 



