INTRODUCTION. 



LIFE-HISTORY AND METAMORPHOSES. 



IN dealing with the life-history and metamorphoses 

 of the Coccidae as set forth in the introductory chap- 

 ters which follow, I have endeavoured to lay before 

 the student a few facts concerning the more salient 

 characteristics of this remarkable group of insects, in 

 which order of form and diversity of habit are not 

 excelled by any other section of the Homoptera. 

 Fuller accounts of the habits of individual species 

 accompany the descriptions of the various genera and 

 species. 



The food-plants of the indigenous Coccids are 

 chiefly deciduous trees and shrubs. Some species are 

 exclusively confined to one food-plant ; while others, 

 less discriminative, feed upon several. Thus, for 

 example, Aspidiotus zonatus, Frauen., *AsterodiaspJ8 

 quercicola, Bouche, Leccunum ciliatum (Newst. MS.), 

 Douglas, feed exclusively upon the oak (Quercus 

 robur) ; Cryptococcus fagi, Barens, upon the beech 

 (Fag-as sylvatica) ; Physokermes abietis, Mod., upon the 

 spruce fir (Abies excelsa) ; Diaspis carueli, Targ., upon 

 the juniper (Juniperus, sp.) ; and Apterococcus fraxii>i, 

 Newst., upon the ash (Fraxinus excelsior); while 

 Mytilaspis pomorum, Bouche, and Chionaspis salicis, 

 Linn., are found upon plants belonging to widely 

 separated orders. 



* Mr. Cockerell considers this a synonym of Aster olecanium vario- 

 losum, Batz. 



