It gives me much pleasure to acknowledge numerous favors and 

 great assistance received in the preparation of this work, from gen- 

 tlemen who have kindly sent me copies of their published works, 

 and have also given me valuable advice or information. Especial 

 mention should be made of Dr. L. O. Howard, Entomologist to the 

 Department of Agriculture, Washington, D. C, who, with his assist- 

 ants, Messrs. Marlatt, Banks and others gave me most valuable 

 help and information during a recent visit to Washington. Espec- 

 ially am I indebted to Prof. T. D. A. Cockerell, who for the past two 

 years has been constantly sending me separata and references to 

 foreign literature, besides giving me all possible assistance in regard 

 to classification and synonomy, the result of his extensive studies on 

 the Coccidae from all parts of the world. To him is due much of 

 whatever value there may be in this catalogue. I feel it not only a 

 duty but a pleasure to say that I never should have prepared this 

 catalogue but for the assistance and constant encouragement of my 

 husband, who has made great efforts to obtain the necessary litera- 

 ture and who has helped me in every possible way. 



This catalogue will doubtless be criticised because of the many 

 changes in generic names, but a study of the original works of the 

 older authors has led to the conclusion that these changes are neces- 

 sary. Entomologists at the present time differ so much in their 

 opinions on classification that it cannot be expected that these 

 changes will meet with universal approval. Professor Cockerell 

 writes me that " the classification of the Coccidae is not yet in a sat- 

 isfactory state. While we know such a small number of the existing 

 forms, and of those we know, we are in so many cases ignorant of 

 the larvae, males, etc. it is utterly impossible to reach final or approx- 

 imately final conclusions in a large number of cases." 



In the preparation of a work like this no one can be more con- 

 scious of its omissions and imperfections than the author, but the 

 study of the'Coccidffi as a whole is still in its infancy, and there will 

 doubtless be great changes made in their classification as further 

 study is made of the group and new species are discovered. It is 

 hoped, however, that notwithstanding its imperfections this work may 

 be of assistance to those engaged in the study of this important 

 family of insects. 



M. E. Fernald. 

 Amherst, Afass., March, Jgo^. 



