CONTROL OF MEALYl^UGS 9 



Smith and Arniitage (16) found that the pupation period of Crypto- 

 laemus in their insectaries was 8 to 12 days, and observations at Waltham 

 siiowed that this period extended from a minimum of 6 days at 80° F. to a 

 maximum of 39 days at 60° F., with an average duration of 11.44 days at 

 70° F. It sliould be noted, Iiowever, that pupation occurred readily at a 

 constant temperature of 60° F. even tliough greatly delayed, wliile at this 

 temperature death occurred liefore otlier developments such as oviposition, 

 incubation of eggs, and larval growtli, were completed. 



Tlie records secured in 1933 are shown in Table 3. 



Length of Life of the Beetles 



'i'lie average length of life of tlie beetles in the greenliouse has been 

 al)out 40 days, although beetles have lived nearly four months when con- 

 tined in jellj^ glass cages and supplied with leaves infested with mealybugs, 

 for oviposition records. Several beetles have lived more than three 

 montlis in the winter and early spring, and one pair was kept alive 114 

 days. In general, the more favorable the temperature and food supply, 

 the sliorter is the life of the beetles, and those having ideal conditions will 

 live less than two months in summer. 



The beetles feed moderately on various stages of the mealybugs but 

 do not seem to show any preference for either eggs, nymphs, or adults. 

 When beetles were fed adult mealybugs only for a period of about two 

 months, they ate approximately three full-grown mealybugs in 2 days 

 at 80° F., and one full-grown mealybug in 2 days at 70° and 60° F. Such 

 feeding is not enough to hold the mealybug in check on greenhouse plants. 



RATE OF REPRODUCTION OF THE CITRUS MEALYBUG 



The average number of eggs laid by the citrus mealybug was determined 

 by placing small larvae and newly hatched crawlers on coleus and gar- 

 denia plants and raising them in the constant temperature cabinets op- 

 erated at 60°, 70° and 80° F. The egg mass was usually completed about 

 five days after the first egg was laid, and crawlers began to hatch from 

 the first eggs at that time. Consequently-, counts were made about five 

 days after the first eggs were laid. As shown in Table 4, oviposition al- 

 though soniewhat delayed at 60' F., proceeds at a much more normal 



Table 4. Number of Eggs L-\id by Citrus Me.\lybug 

 Waltham, Mass., 1935 



Xumber of Number of Eggs Laid Per Mealybug 

 Temiieratuie Mealybugs Total Number 



•bserved of Eggs Laid Ma.ximum 



Average Greenhouse 



(45°-70° F.) 10 



Constant 80° F. 11 



Constant 70° F. 15 



Constant 60° F. 9 



