24 THE EEPOET OF THE No. 36 



and sweet corn. As the. plant increased in length and the larva? on the rolled up 

 leaves were exposed to light, they bored into the stalks, which by the end of July 

 in the early planted corn began to break over. 



By the third week in July in the very early sweet corn, and to a much less 

 extent in the flint, the majority of the larvae were full grown. At that time a 

 very small second brood developed in the very earliest planted sweet corn, involving 

 but a fraction of one per cent, of the larva?. In this sweet corn 10 pupse in all 

 were collected between July 21st and 26th and 4 pupa? were secured from larva? 

 collected at the same time. From these pupa?, after a period of 13 days, 2 male 

 moths and 1 female moth were reared. The female laid fertile eggs, the larvie 

 from which established themselves on a corn plant in an experimental cage. The 

 only other evidences of the second brood were 1 pupa and 2 female pupal cases 

 from the earliest flint corn, an adult male in late July, an egg mass found on| 

 August 9th and a few 3rd instar larva? taken late in August. 



The larva? in all varieties of the later corn, matured distinctly later on the 

 average and showed no signs of developing a second brood, but prepared for 

 winter about the middle o,f August and where not disturbed, would probably not 

 move until spring. At harvest time about the last of August and in early Sept- 

 ember in a flint corn field showing 70% total loss, the estimated number of larva? 

 per acre was 191,800. Of these 27% were within 12 inches of the ground and 

 a four inch stubble carried 28,079 larvte, 6.82% of the larval population. 



There was no movement of any import in the standing field corn in the fall, 

 the distribution in the middle of October being practically the same as at the end 

 of August. However, there is a noticeable movement outward and downward in 

 the stalks in shock, but none of any importance from the shock to the ground and 

 neighbouring stubble. 



The date of sowing was closely correlated with the degree of infestation, the 

 larval population and the total loss both in experimental and field conditions. 

 In general, corn sown before May 24th was either practically ruined or suffered 

 severe loss; that sown between May 24th and June 1st was heavily infested, 

 but suffered relatively less or but slight actual loss, depending of course upon the 

 type of corn ; while the corn sown after June 1st, although in some cases showing 

 a fairly high percentage of infestation carried few larva? and practically no loss 

 except in the case of sweet corn. Thus, on one farm of three corn patches 

 within 100 yards ©f each other, the sweet corn sown April 25th carried a larval 

 population of 234.200 per acre with a loss of 100%; sweet corn planted June 1st 

 developed an infestation of 75% : and carried a larval population of 80,000 per acre 

 with a loss of 20%; while flint (smut nose yellow) planted May 22nd, only carried 

 54,400 per acre, a stalk infestation of 67% and a total loss of not more than 10%. 

 The sweet corn here doubtless protected the flint by attracting a large number 

 of the moths. 



In the experimental plots the effect of the date of planting shows up most 

 clearly, as can be seen in the tabulation below, though here the loss was slight 

 and the larval population meagre, the corn all being planted after May 24th. 



