CHAPTER XXIX 



THE LEPIDOPTERA 



The Lepidoptera are the moths and butterflies, which form one of 

 the largest and most noticeable groups of insects. Its members are 

 found in all countries and their large size in many cases, their brilliant 

 colors and the habits of their larvae as well as the injuries they cause, 

 have attracted much attention. 



The adults have four, large, membranous wings in most cases (a few 

 have lost their wings), more or less completely covered by overlapping 

 scales making the wings opaque where these are present. Colors of the 



wings are due either to the presence of 

 pigments in the scales: to optical colors 

 caused by the surfaces of the scales break- 

 ing up the light striking them; or by both 

 factors together. 



The mouth parts of the adult are greatly 

 modified from those of chewing insects, 

 though enough remains to show that the 

 ancestors of the group must have fed by 

 chewing. The development of the parts 

 varies in different species, some of the 

 lower forms having as a whole, a much 

 closer resemblance to the condition in 

 chewing insects than is the case with most 

 of them. In one group, the mouth parts 

 are sufficiently of the mandibulate type to 

 enable the insects to feed on pollen. 



In general a labrum or front lip is evi- 

 dent, but the mandibles are practically lost. 

 The maxillae are extremely modified, a por- 

 tion of each contributing its half to the formation of a proboscis or tongue 

 (Fig. 227). This is a flexible organ varying greatly in length, its two 

 halves so interlocking as to form a tube between them, through which, 

 when completely developed, fluids may be drawn into the mouth. The 

 degree of development of the proboscis differs greatly in different 

 Lepidoptera, and while it is functional in perhaps the majority of the 

 group it is only partly developed or even rudimentary and useless in 

 others. Such Lepidoptera evidentlj^ do not feed while adult. 



230 



Fig. 227. — Diagram of head of 

 a Lepidopterous insect, showing 

 the tongue. {From a drawing by 

 M. F. Webster.) 



