196 THE STUDY OF INSECTS. 



usually hold the wings erect in a vertical position like 

 butterflies; often the fore wings are thus held while the 

 hind wings are extended horizontally. The antennae are 

 thread-like, and enlarged towards the tip ; but in most cases 

 the extreme tip is pointed and recurved, forming a hook. 

 The abdomen is usually stout, resembling that of a moth 

 rather than that of a butterfly. This division includes two 

 families. 



The Butterflies. The butterflies fly by day ; and when 

 at rest they fold the wings together above the back in a 

 vertical position. The antennae are thread-like with a club 

 at the tip, which is never recurved so as to form a hook. 

 The abdomen is slender. This division includes the last 

 four families described in this chapter. 



Classification of the Lepidoptera. 



{For Advanced Students.') 



The study of the classification of the Lepidoptera is beset by a 

 peculiar difficulty. As these insects are clothed with scales com- 

 paratively little of their structure can be examined without injury to 

 the specimens studied. Fortunately, however, it has been found 

 that the various modifications of the framework of the wings afford 

 excellent clues to the relationships of the different groups; and these 

 modifications can be determined in most cases without serious injury 

 to the specimens. The structure of the antennae also can be easily 

 studied, and in many cases affords much help in determining the zoo- 

 logical position of an insect. 



The first step to be taken in the study of the classification of 

 these insects is to become thoroughly familiar with the nomenclature 

 of the wing veins ; this is given on pages 64 to 66. It is a good plan 

 to take several of the larger moths and butterflies and make draw- 

 ings showing the courses of the veins of the wings in each, carefully 

 indicating the names or numbers of the veins on the drawings. 

 The making of such drawings will be of much use in fixing the ar- 

 rangement of the veins in the student's mind. It should be remem- 

 bered that veins IV and VI are not developed in this order. 



As the scales on the lower surface of the wings are more closely 

 applied to the wings than are those on the upper surface, the veins 

 can be best seen when the wings are examined from below. The 



