ORDER LEPIDOPTERA: MOTHS AND BUTTERFLIES 241 



which projects from the root of the hind wing and bites 

 into a flap or tuft of scales, known as the retinaculum, on 

 the under side of the front wing ; or (2, as in butterflies and 

 some large moths) by a flange of the inner part of the 

 anterior border of the hind wing, which rides under the 

 front wing ; or (3, as in a few moths) by a slender finger- 

 like stay, known as the jugum, which projects backwards 

 from the axil of the front wing. The scales that cover the 

 wings are arranged in regular overlapping rows like the 

 slates on a roof. The colouring of the wings is effected 

 by the scales, and is due either to pigment, or to surface 

 diffraction of light, or (in the case of white) to occluded air. 

 The females of some moths are wingless. 



The abdomen, which like other parts of the body, is 

 thickly covered with hairs' or scales, is composed in the male 

 of 8, in the female of 7, visible segments. 



The eggs, which are of varied shape and sculpture, are 

 often laid on the particular food-plant of the larva. The 

 larva, or caterpillar, has a distinct head and powerful 

 mandibles; 3 distinct thoracic segments, each, as a rule, 

 with a pair of short legs, which are segmented and end in 

 a claw ; and 10 abdominal segments, the last of which, and 

 generally some of those in front of it, bears a pair of fleshy, 

 unsegmented pseudopods the tips of which are burred with 

 minute booklets. The larva has a pair of silk-glands which 

 open at a prominence, the spinneret, in the middle of the 

 labium : it feeds voraciously, usually on foliage, but some- 

 times burrowing into leaves, or into fruits and seeds, rarely 

 upon animal matter. The pupa in most butterflies is 

 " obtected," «>., is an exposed chrysalis physiologically pro- 

 tected by the hardened secretion or pupal skin that binds 

 down all the appendages ; but in most moths the pupa is, 

 further, mechanically protected by a cocoon of some sort, 

 which is constructed, in whole or part, of silk spun by the 

 larva when preparing to pupate. 



The order is composed of two groups — Rhopalocera, or 

 Butterflies, and Heterocera, or Moths. 



In the Rhopalocera {p6-KaXov = z. club; /ce/)a? = antenna) 

 the antennae are clubbed at the tip, the wings are held 

 together by a flange of the posterior wing, and when the 



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