153 JOURNAL OF ECONOMIC ENTOMOLOGY [VoL 3 



their liking they are found elsewhere only occasionally. After the 

 com ripens they may be found in great numbers in alfalfa, in patches 

 of velvet leaf, on bladder ketmia, and on ground cherry. This fall 

 they were especially abundant in alfalfa. 



The possible number of broods was determined in an outdoor,, 

 screen insectary by getting eggs from the first moths that emerged 

 in the spring which would oviposit in confinement, breeding these 

 through to moths, taking eggs from the first to emerge, and so con- 

 tinuing throughout the season. Chart No. 1 will serve to give a 

 summary of the results. 



Examination of this chart shows that the insect experiences three 

 full broods and a partial fourth at Manhattan. The first extends 

 from June 8, 1909, to July 18, 1909, occupying 40 days, under an 

 average mean temperature of 76.1°F. and relative humidity of 78.6° ; 

 the second from July 18, 1909, to August 21, 1909, occupying 34 

 days, under an average mean temperature of 77.6°F. and relative 

 humidity of 77.2° ; the third from August 21, 1909, to October 13, 

 1909, occupying 53 days, under an average mean temperature of 

 72.8°F. and relative humidity of 67.3 °F. The fourth brood is only 

 partial and the young do not reach maturity. Most of the third 

 brood of pupae do not transform to adults in the fall but remain in 

 the ground as the overwintering brood. 



The actual number of broods has been determined by making fre- 

 quent and regular countings of the number of eggs borne by corn 

 plants of different ages and by observing the prevalence of moths 

 and the age of larvre in the field. The variation in the number of 

 eggs per corn plant for different counts is not sufficiently pronounced 

 to reveal the presence of very distinct maximums indicating distinct 

 broods until the tremendous increase due to the arrival of the third 

 brood appears. The results of plotting the counts for 1908 and 1909 

 from field corn and constructing curves are shown in chart No. 2. 



The observer experienced difficulty in the field in separating the 

 first brood from the second, and still more in separating the second 

 brood from the third, and after the arrival of the third lost all dis- 

 tinction between the broods. From the time the third brood came on 

 moths could be found in large numbers and eggs and larvte in all 

 stages at any time. The number of broods as determined by field 

 observations alone is three, but a partial fourth might very well 

 occur as all above-ground stages of the insect may be found until 

 heavy frosts. 



Study during 1908 had indicated: (1) that early winter plowing 

 would, as has been stated in the literature of this insect, greatly 



