Life history — Continued. Page. 

 The egg — Continued. 



Shrinking of infertile eggs 51 



Eating of shells and eggs by newly hatched larvae 51 



Percentage of eggs that hatch 52 



Length of the egg stage 52 



Effect of reduced temperatures 53 



Effect of atmospheric conditions 54 



Effect of submergence on eggs 54 



Eggs destroyed by storms 55 



Effect of sun on eggs 55 



The larva 55 



Descriptions of instars 57 



Possible causes of color variation 62 



Duration of larval instars 63 



Growth during the larval instars 64 



Influence of external conditions on growth 66 



Number of molts 67 



Process of molting 67 



Habits of newly hatched larvae on cotton 68 



Effect of external conditions on newly hatched larvae 68 



Character of injury 68 



Character of injury to corn 69 



Character of injury to cotton 69 



Character of injury to other plants 70 



Choice of food by larvae 71 



Relative attractiveness of Upland and Egyptian cottons 71 



Comparative inj ury to early and late cotton 72 



Amount of damage done by a single larva 74 



Damage to young corn 74 



Damage to ears of corn ... 75 



Damage to cotton ^ 76 



Number of larvae on a single plant 78 



Relation to the number of eggs laid 78 



Percentage of corn plants infested - 78 



Cannibalism 79 



Leaving the plant and entering the ground for pupation 80 



Formation of the pupal cell 81 



Variations in the form of the pupal cell 82 



Pupation in other situations 83 



Changes undergone in the formation of the pupa 83 



The pupa 84 



Description of pupa 84 



Length of the pupal stage 84 



Effect of external conditions - - - 86 



Heat 87 



Soil 87 



Mortality during the pupal stage 88 



The adult 89 



Emergence 89 



Description of moth 89 



Size of moths ' 90 



Variation and possible causes 90 



Anatomy and sexual differences 91 



