LEPIDOPTERA 



635 



clear-winged sphinxes and certain euchromiids, that have a greater or 

 less part of the wings devoid of scales; but they are exceptions. 

 Here it is the rule that the greater part of one or both pairs of wings 

 are free from scales; hence the common name, clear-winged moths. 

 In a small number of members of this family the wings are scaled 

 throughout. 



These insects are of moderate size; as a rule they have spindle- 

 shaped antenuce, which are terminated by a small silky tuft ; some- 

 times the antenuce are pectinate; the margins of the wings and the 

 veins of even the clear-winged species are clothed with scales; and 

 at the end of the abdomen there is a fan-like tuft of scales. 



Fig. 778. — Wings of Synanthedon exitiosa. 



The fore wings are remarkable for their extreme narrowness and 

 the great reduction of the anal area (Fig. 778) ; while the hind wings 

 have a widely expanded anal area. The number of anal veins in the 

 hind wings varies greatly within the family, the number ranging from 

 two to four; where there are four anal veins, it is probably the third 

 anal vein that is forked. 



Another remarkable feature of the wings of these insects is that 

 in the female the bristles composing the frenulum are consolidated 

 as in the male ; this condition exists in the females of a few members 

 of other families. The females of the ^geriidae possess a frenulimi 

 hook ; but this is not so highly specialized as that of the male. 



In addition to the presence of a highly specialized frenulimi 

 and a frenulum-hook, there is a unique provision for holding the 

 fore and hind wings together. The inner margin of the fore wing is 



