CONTROL OF MEALYBUGS 11 



number of eggs was increased by five or ten wlienever the daily quota 

 was eaten. It is possible, however, that larvae would have eaten more 

 eggs than were supplied in some of the cages, especially during the periods 

 of greatest feeding just before moulting. 



Length of Life of Larvae 



Througliout the studies only one Cryptolaemus larva was reared from 

 egg to pupa on mealybug eggs at a constant temperature of 60° F. This 

 individual pupated 99 days after it hatched. At this temperature the 

 other larvae usually died during the second instar, although in 1935 one 

 individual lived 38 days. The average length of life for those larvae which 

 did not complete their growth was 25.77 days in 1935 and 12.11 days in 1937. 



The larvae which pupated lived slightly longer at 70° F. than at 80° F., 

 the average number of days required to complete their growth at 70° F. being 

 6 days longer in 1935 and 11 days longer in 1937. At both 70° F. and 80° F.. 

 the growth and development of the larvae appeared normal. At 80° F., how- 

 ever, there was more uniformity among the individuals, especially in 1937 

 when the length of life of 10 larvae, from hatching to pupation, varied only 

 4 days, compared with a variation of 19 days at 70° F. in 1935. These re- 

 sults are summarized in Table 5. 



Table 5. Length of Life of Cryptolaemus Larvae (From Hatching 



TO Pupation) When Feeding on Citrus Mealybug Eggs at Constant 



Temperatures. Waltham, Mass., 1935 and 1937. 



*None pupated or completed larval growth. 

 **Only 1 larva completed growth and jiupated. 



Number of Mealybug Eggs Eaten 



In these experiments larvae which completed their growth ate from 

 1200 to 1400 eggs of the citrus mealybug during their life, or an average 

 of 25 to 36 eggs per day. 



In 1935 the average larva confined at 80° F. ate about 30 more eggs 

 than those confined at 70° F., but in 1937 those confined at 70° F. ate 

 more than those confined at 80°' F., largely because they lived 11 days 

 longer. 



The only larva which completed growth at 60° F. consumed 1328 eggs, 

 which is well within the range of the number eaten at the higher temper- 

 atures, indicating that although temperature and other environmental con- 

 ditions may cause the length of life and rate of feeding to vary, a rather 



