CONTENTS. 



CHAPTER I. 



THE CLASSIFICATION OF INSECTS. 



Introduction. Stages in the Life of an Insect. Classification of 

 Insects. Characters derived from the Wings ; from the parts of 

 the Mouth; from the Metamorphoses. The Classes of Insects: 

 Hymenoptera, Strepsiptera, Coleoptera, Euplexoptera, Orthoptera, 

 Thysanoptera, Neuroptera, Trichoptera, Diptera, Aphaniptera, 

 Heteroptera, Homoptera, Lepidoptera page I 26 



CHAPTER II. 



THE INFLUENCE OF EXTERNAL CONDITIONS ON THE FORM AND 



STRUCTURE OF LARV/E. 



Larvse depend partly on the group to which they belong. Wood-eating 

 Larvae. Larvae of Lamellicorns. Larvse depend also in part on 

 mode of life. Larvse of Hymenoptera, of Sirex ; of Tenthredo ; of 

 Ichneumons; of Bees. Rudimentary legs of Bee Embryo. Beetles, 

 Weevils, Scolytus, Crioceris, Sitaris, Metamorphoses of Pteromalidae. 

 Platygaster, Polynema. Influence of external conditions. Deve- 

 lopmental and adaptive Metamorphoses .... Page 27 41 



CHAPTER III. 



THE NATURE OF METAMORPHOSES. 



The life history of an Insect must be considered as a whole. Vagueness 

 of the term Larva. Some larvae much more advanced than others. 

 Organs develope in different order, in different groups. Sup- 

 pressed stages. Apod condition of Phryganea ; of Aphis ; of 



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