CONTROL OF MEALYBUGS 21 



SUMMARY 



Cryptolaemus montroimeri ]\Iuls., which is one of the imporant natural 

 enemies of mealybugs infesting citrus trees in California, has been reared 

 on the citrus mealybug and the long tailed mealybug on gardenias and 

 the Mexican mealybug on chr_vsanthemums, under normal conditions in 

 Massachusetts greenhouses. 



In experiments, Cryptolaemus larvae ate about 1325 mealybug eggs, the 

 equivalent of 3 or 4 mealybug egg masses, during their life and completely 

 eradicated an average mealybug egg mass in 9 or 10 days. 



A constant temperature of 60° F. definitely retarded the development 

 and activity of the beetle so that it did not hold the mealybug in check, 

 I)ut satisfactory results were obtained at 70° and 80° F. 



Practical control of mealybugs by this predatory beetle was secured: 



1. From April 1 to September 1, when a temperature above 70° F., 

 wliich would stimulate the development and activity of the beetle, could 

 be maintained. 



2. \\hen the infestation of mealybugs was great enough to provide 

 adequate food without causing unprofitable injury to the plants. 



3. On plants wliich will tolerate warm growing conditions favorable 

 to the activity of tlie beetle. 



4. When the beetles were liberated at the rate of 1 for each gardenia 

 plant or 1 for each 2 chrysantliemum plants. 



.T. When the use of insecticides necessary to control other pests did 

 not kill the majority of the beneficial predators. 



\\'hen these conditions were provided, as described in detail, Cryptolaonns 

 luontroucicn controlled or eradicated a heavy infestation of mealybugs within 

 ur 10 weeks after tiiey had been successfully liberated and a normal 

 numl)er of second generation larvae had developed. 



LITERATURE CITED 



1. Armitage, H. M. Timing field liberations of Cryptolaemus in the 

 control of the Citrophilus mealybug in the infested citrus orchards 

 of southern California. Jour. Econ. Ent. 22:6:910-915. 1929. 



2. Clausen, C. P. Mealybugs of citrus trees. Calif. Agr. Expt. Sta. 

 Bui. 258:39. 1915. 



3 Insect parasitism and biological control. Ent. 



Soc. Amer. Ann. 29:2:201-223. 1936- 



4. Cole, F. R. Natural control of the citrus mealvbug. Tour. Econ. Ent. 

 26:4:855-864. 1933. 



5. Essig, E. O. Natural enemies of the citrus mealybug, II. Pomona 

 Col. Jour. Ent. 2:3:260-274. 1910. 



6 Citrus mealvbug. Pomona Col. Jour. Ent. 



2:4:289-320. 1910. 

 7. Haug, G. W., and Peterson, Alvah. The effect of insecticides on a 



beneficial Coccinellid, Hippodamia couvcrgciis Guer. Jour. Econ. Ent. 



31:1:87-92. 1938. 



