WINGS 3 I 5 



the functional importance of which is unknown, between the 

 claws. 



Wings. — The wings are the most remarkable feature of this 

 Order ; it is to them that butterflies owe their beauty, the sur- 

 faces of the wings being frequently adorned with colours and 

 patterns of the most charming and effective nature. These 

 effects are due to minute scales that are implanted in tlie wing- 

 membrane in an overlapping manner, somewhat similar to the' 

 arrangement of slates on the roof of a house. The scales are very 

 readily displaced, and have the appearance of a silky dust. We 

 shall describe their structure and allude to their development 

 subsequently. The wings are usually of large size in com- 

 parison with tlie Insect's body : in the genus 3forpho, the 

 most gorgeous of the butterflies, they are enormous, though the 

 body is small ; so that when deprived of these floats the Insect is 

 insignificant. The great expanse of wing is not correlative with 

 great powers of flight, though it is perhaps indicative of flying with 

 little exertion ; for the small-winged Lepidoptera, Sphingidae, 

 etc., have much greater powers of aerial evolution than the large- 

 winged forms. The area of the wing is increased somewhat by 

 the fact that the scales on the outer margin, and on a part or on 

 the whole of the inner margin, project beyond the edges of the 

 membrane that bears them : these projecting marginal scales are 

 called fringes. In many of the very small moths the actual size 

 of the wing-membranes is much reduced, but in such cases the 

 fringes may be very long, so as to form the larger part of the 

 surface, especially of that of the hind wings. Frequently the 

 hind wings are of remarkable shape, being prolonged into pro- 

 cesses or tails, some of which are almost as remarkable as those 

 of Nemoptera in the Order Neuroptera. 



The wings are very rarely absent in Lepidoptera ; this occurs 

 only in the female sex, no male Lepidopterous imago destitute of 

 wings having been discovered. Although but little is known of 

 the physiology of flight of Lepidoptera, yet it is clearly important 

 that the. two wings of the same side shovild be perfectly coadapted 

 or correlated. This is effected largely by the front wing over- 

 lapping the hind one to a considerable extent, and by the two 

 contiguous surfaces being pressed, as it were, together. This is 

 the system found in butterflies and in some of the large moths, 

 such as Lasiocampidae and Saturniidae ; in these cases the liind 



