CHAPTER III 



EXTERNAL ANATOMY 



The sclerites and sutures of the Hemiptera even in the species 

 of the most generalized families are generally modified in form 

 and distinctness from the same parts in all insects of the orthop- 

 teran type. In the specialized Gularostria the sutures are effaced 

 for the most part. The intersegmental coriae are frequently 

 wanting in the Coccidae and, when present, are usually indicated 

 only as slight transverse furrows. A study of the external anatomy 

 of the coccids consists in an examination and identification of the 

 body regions, the appendages, and the numerous new or secondary 

 structures that have arisen as a result of their peculiar mode of life. 



The body of a coccid, while different in external form from 

 that of most Hemiptera, has retained certain characters showing 

 conclusively their relationship to the other families of the order. 

 The variation in external structure is not limited to differences 

 from the other families of the order, but there is a great dissim- 

 ilarity in form even among the various subfamilies of Coccidae, 

 particularly among the adult females. This difference has un- 

 doubtedly resulted from the dissimilarity in their habits and from 

 the diverse ways in which the females shield their progeny. Eggs 

 are laid in many species and they are protected by a waxy covering 

 which varies greatly in form, consistency, and position in the 

 different genera. With the variation in the waxy excretion there 

 is a corresponding variation in the structures of the bodj' of the 

 insect that produces the excretion. 



The two sexes, as pointed out, are very different in size, form, 

 and structure. The adult males are distinctly insect-like in form. 

 Their parts are normal in form and arrangement and do not differ 

 markedly, except in the loss of mandibles and maxillae, from those 

 of other winged insects. The adult females on the contrary are 

 usually more or less grub-like in form. They possess many struc- 

 tures not found in the males. The classification is based almost 

 entirely upon the females and the following descriptions unless 

 otherwise stated refer only to them. 



Body-wall. — The exterior covering or body-wall of coccids is 

 composed of the three layers common to other insects, cuticle, 

 hypodermis, and basement membrane. 



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