88 THE CAUSES WHICH PEOPAGATE 



The attractive quality of insects^ colours from the foregoing 

 appears nearly that presented to the human eye, and, utilised in 

 sedentary or aerial display, originates phenomena of love and 

 rivalry, battles, dances, and gregariousness in evident paral- 

 lelism with those evoked by music. But this attractive 

 virtue, which must be considered as stimulative, does not reside 

 especially in either sex, as some at first sight might be inclined 

 to assert ; for we find conspicuous colourisation, though for the 

 most part distinguishing the males, sometimes by a species of 

 inversion appearing in the females ; the sexes also are often very 

 similar in hue. And the reason of this is that the females very 

 generally attract the eager males by sedentary display, of which 

 the moth kind affords notable instance. Here we may remark 

 the paler hues of many heavy Bombycina females who exhibit on 

 herbage, and the grey, white, or satiny shades of moths that 

 repose on tree trunks, sexually marked in the Gipsy Moth, 

 who is rendered in measure terrestrial by her limp wings. Others 

 more or less apterous, like the A^apourers and Psychidse, owe 

 what little chromatic attraction they possess in all appearance to 

 their conspicuous cocoons. 



To ensnare many of these kinds, it is only necessary to expose 

 a female in a box covered with gauze ; males of the Yapourers, 

 Gipsy Moth, and Oak Eggars are all then readily enticed, 

 even when none are visible in the sky. In the case of 

 the Gipsy a pungent odour exuded during pupation doubt- 

 less adds to the allure, and to many such an effluvia has seemed 

 necessary in all cases, seeing that the eager suitors are endowed 

 with a keenness of perception approaching the marvellous, and 

 come from a range it is difficult to assign to insect vision. But 

 this matter is wanting in proof. In a state of liberty the smaller 

 moths are quite as attractive for their males as these diurnal 

 members of the silk-spinning group. White Geometrina, such 

 as the species of Acidalia, may often be observed climbing the 

 sprays of plants to display at nightfall ; and these kinds assemble 

 the males in numbers, although, singular to say, species of the 

 Geometridse that exhibit delicate tints of evanescent green prove 

 no less attractive. At the call of passion individuals of tinier 

 Tortricina and Tineina are often noticed surrounded Avith quite a 

 circle of admirers. 



