2 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.78 



The host records of Coccophagus are meager and many of them 

 are incorrect, due to unsatisfactory determinations. Practically all of 

 the Australian species obtained by Girault were described from one 

 or several poorly preserved specimens captured by sweeping; con- 

 sequently their hosts are unknown. The life histories of only a few 

 species have been studied and, so far, they have proven to be essen- 

 tially primary in habit. It is not safe to conclude that all the 

 species will prove to be primaries, since they are adaptable when 

 competing for the possession of a host and under certain conditions 

 develop as secondary parasites. It is but a short step from acci- 

 dental secondary parasitism to obligatory secondary parasitism. A 

 species of Euxanthellus^ a genus very closely related to Cocco'phagus^ 

 is known to be an obligatory hyperparasite. 



This paper is No. 172, of the studies made at the University of 

 California, Graduate School of Tropical Agriculture and Citrus 

 Experiment Station, Riverside, California. It is based largely on a 

 study of specimens in the United States National Museum, the 

 Brisbane Museum, the E. W. Rust collection, the Silvestri collection, 

 and the British Imperial Bureau of Entomology collection. The 

 types of all species described as new in this paper are to be deposited 

 in the United States National Museum. For the privilege of study- 

 ing this material the author expresses his appreciation to Dr. L. O. 

 Howard, Dr. H. A. Longman, Dr. F. Silvestri, Dr. Guy Marshall, 

 Mr. A. B. Gahan, and Mr. E. W. Rust. To Dr. F. Silvestri I am 

 indebted for his kindness in loaning me the cotypes of the species 

 which he described and for the privilege of describing several new 

 species which he collected. To Mr. Gahan and Mr. Timberlake I 

 am especially indebted for much assistance freely given. Mr. Tim- 

 berlake loaned his unpublished notes, Mr. Gahan critically read the 

 first draft of the manuscript and suggested changes which have been 

 made. The help which Mr. Gahan and Mr. Timberlake have given 

 is more fully acknowledged in the text. 



GEOGRAPHICAL DISTRIBUTION 



The distribution of Coccophagus has been greatly influenced by 

 commerce, for like the coccids which they inhabit, species of Cocco- 

 phagus are particularly liable to accidental transportation through 

 the interchange of nursery stock. They pass the greater part of 

 their life cycle within their hosts, and when inhabiting coccids 

 they are easily transported from one locality to a new one. Many 

 of the coccids that serve as hosts of Coccophagus, infest plants of 

 economic importance and are transported with nursery stock from 

 one country to another. For this reason it is not always possible to 

 determine the native habitat of a cosmopolitan species nor is it safe 

 to assume that a species is an indigene of the particular country 



