April, '10] 



HEADLEE: THE CORN EAR- WORM 



151 



eggs on various useful plants and on weeds, but seem to prefer corn 

 plants to anything else. Indeed, so emphatically is this the case 

 that from the date of emergence to the hardening of the corn, few- 

 eggs are laid anywhere else in the vicinity of cornfields. Until silking 

 begins the eggs are placed on the corn blades and the larvae feed on 

 the tender curl of the corn. After silking commences the eggs are 

 laid almost exclusively on the silk. After the silks dry and shrivel, 

 so long as the stalk, blade and husks remain green, a few eggs are 

 deposited. Gradually all such oviposition ceases and the moths turn 

 their attention to various weeds in and around the cornfields and to 

 adjacent fields of alfalfa. At this time they deposit hundreds of 

 eggs on alfalfa, red clover, velvet leaf, foxtail, bladder ketmia, lamb's 

 quarters, sunflower, soy beans, millet, Amaranthus, sp. and smartweed 

 {Polygonum pennsylvanicum) . 



CHART NO. I ^^__^_ 



CD 

 Ld 

 O 

 < 



I— 

 CD 



RRnnn 



ADULT_ 



EGG 



LARVA. 

 PUPA 



^ 



HATE 



? 9 



S 



—^ 3 dg %( <^/ 



^8 



2 



CO CD 



E 



H 



s s s 



Chart No. 1. — Diagram sliowiiig the possible numljer of broods of corn ear- 

 worm at Manhattan, Kan. l=pair of first-brood adults from emergence to 

 oviposition; 2=the average of 40 eggs from deposition to hatching; 3=the 

 avei'age of 10 larvae from hatching to pupation; 4=the average of 9 pupse 

 from pupation to emergence of adult; 5=pair of second-brood adults from 

 emergence to oviposition; 6=the average of 30 eggs from deposition to hatch- 

 ing; 7=the average of 10 larvae from hatching to pupation; 8=the average 

 of 10 pupae from pupation to emergence of adult; 9=pair of third-brood 

 adults from emergence to oviposition; 10=the average of 25 eggs from 

 deposition to hatching; ll=the average of 11 larv£e from hatching to pupa- 

 tion; 12=the average of 9 pupae from pupation to emergence of adult; 

 13=pair of fourth-brood adults from emergence to oviposition; 14=that 

 portion of the third brood of pupae which forms the overwintering brood. 



While there Is no doubt whatever that the larvae prefer corn and 

 will be found upon it so long as it is present and sufficiently succu- 

 lent for food, there is also no doubt that they are able to develop 

 upon a diet of alfalfa, bladder ketmia, velvet leaf and sorghum and 

 are able to finish their growth on many species other than these. 

 From the time the larvae appear until the corn grows too hard for 



