BIOLOGICAL CONTROL OF MEALYBUGS IN GREENHOUSES 



By W. D. Whitcomb, Research Professor of Entomology^ 



INTRODUCTION 



Biological control, accomplished by the artificial rearing and liberation of 

 parasitic and predatory insects, has been an approved method for combating 

 mealybugs on citrus trees for many years (18). This work has been most 

 extensive and successful in the United States in the citrus orchards of Cali- 

 fornia (14), where experimental studies of various imported insect enemies 

 of the citrus mealybug {Pseudococcus citri Risso) and the citrophilus mealy- 

 bug (Pscudococcns gahani Green) (15) have led to practical control of these 

 pests. In the reports of this work, especially those of .'^rmitage (1) and 

 Clausen (2) in California, great importance is placed on the necessity for 

 temperatures and relative humidities that are favorable for the development 

 of the beneficial insect, and it seemed that these conditions either existed nor- 

 mally or could be provided easily in Massachusetts greenhouses, where the citrus 

 mealybug is a destructive pest on gardenias, coleus, and other flowering plants. 



The beneficial insect which was used in these studies in eastern Massachu- 

 setts greenhouses was the Australian Mealybug Destroyer, Cryptolaanus mon- 

 trouzicri Mulsant. a ladybird beetle of the family CoccinelUdac. 



HISTORY OF CRYPTOLAEMUS MONTROUZIERI 

 IN THE UNITED STATES 



Cryptolacmiis uiontrouzicri Muls. is a native of Australia, and was first intro- 

 duced into this country at California in 1892 by Albert Koebele. The first 

 liberations were made in citrus orchards heavily infested by the citrus mealy- 

 bug. The colonies which were liberated in San Diego and Santa Barbara 

 Counties have thrived under favorable climatic conditions (16). In many other 

 parts of the State, however, new liberations have been necessary whenever 

 mealybug outbreaks occurred, and hundreds of thousands of these beetles are 

 now raised in insectaries to supplement the surviving population (13). In 

 1930, colonies of Cryptolaemus were liberated in Florida (20) where they sur- 

 vived, but supplementary liberations were needed to give profitable control of 

 mealybugs. 



After the success of the original importation in California was established 



'The writer gratefully acknowledges the assistance of Harold \. Wilson, formerly Tech- 

 nical Assistant, and William Garland, Technical Asatistant, who made many of the observa- 

 tions reported "in this Bulletin. 



Legend for Figure 1. 



A. Arrow points to eggs of C. montrouzieri which have been moved to the edge of the 

 egg mass of the citrus mealybug in which they were laid (x lla)- 



B. Above, two larvae of the citrus mealybug; below, two larvae of C. montrouzieri 



(X 11/2). 



C. Pupa of C. montrouzieri, covered with the white waxy filannents of the larval skin 

 within which it pupated (x 3'/2). 



D. Beetle of C. montrouzieri (x 3',2). 



E. Cryptolaemus montrouzieri beetles in celluloid capsules packed in mailing tube as re- 

 ceived by air mail. 



