214 MANUAL OF VEGETABLE-GARDEN INSECTS 



middle of the back divided by a narrow white line. The corn 

 ear- worm might be mistaken for an army- worm of the summer 

 brood, which it somewhat resembles, but may be distinguished 

 by the granulose skin which under the microscope appears as 

 if studded with minute hob-nails. 



When mature, the caterpillar leaves its food plant, descends 

 to the ground and burrows into the soil in a slanting direction 

 to a depth of two to seven inches, leaving the passage filled 

 with loose earth. It then constructs a 

 tunnel almost to the surface of the ground 

 for the emergence of the moth. This 

 tunnel is lined with compacted soil and a 

 thin layer of silk. After completing the 

 exit tunnel, the larva retreats to the en- 

 larged lower part of the burrow and there 

 transforms to a pupa. The pupa is 

 smooth, brownish, f to nearly 1 inch in 

 length and usually rests in a slanting posi- 

 tion with the head upward. Pupse formed 

 by the summer broods are usually found 

 nearer the surface than those which winter 

 over. The period passed in the pupal stage 

 varies with the season. In the summer it is 

 about two weeks and in the fall three weeks 

 or more. The number of generations produced annually varies 

 with the length of the season. Throughout the cotton belt there 

 are probably four generations and sometimes a few moths of a 

 fifth brood may emerge. In southern Texas and Florida seven 

 generations may develop. In New Jersey and in other northern 

 localities where the insect is a serious corn pest, only two 

 or three generations occur. Farther north there is probably 

 only one brood. After the first generation, the later ones 

 become badly mixed, owing to the overlapping of broods caused 

 by the irregular emergence of the moths, and the unequal 



Fig. 135. — The corn 

 ear- worm, dorsal 

 view (natural size). 



