520 



Journal of Agricultural Research 



Vol. VI, No. 14 



Table II. — Table of molts and instars of Chrysopa califorvica at Tempe, Ariz. 



PART I. FEBRUARY, 1915. AVERAGE MEAN TEMPERATURE, 54° F- 



1 Died. 



From these records it is seen that a C. calif ornica larva under natural 

 conditions, eating both large and small aphids, must often consume 300 

 or 400 of them during the course of its development. The economic 

 value of these larvae is thus seen to be enormous. It was found that an 

 average of about 1 4 full-grown adults of ,4 phis maidis were consumed in 

 the first instar, 4 to 7 aphids being eaten the first day after hatching. 

 The duration of the first instar was found to vary with the temperature, 

 it being from 4 to 9 days and the average period about 6 days in length. 

 A great many more aphids are consumed during the second instar than 

 in the first. This instar averages nearly a day shorter, being 7 days 

 during March and 3^3 days during October, 20 being the average number 

 of aphids eaten by each of 15 larvae during the former period and 31 

 during the latter. In actions and habits it is largely the same as the 

 first instar except for the increased power of destroying aphids 



