54 THE CAUSES WHICH PROPAGATE 



wing's, the group that flocks to our sugar-pots and evening 

 lanterns from the long grass and flowery shrubs, we find the 

 " fans/^ with little exception, in the males, although, for 

 some reason unknown, they are sometimes altogether wanting. 

 They may be discovered by means of a needle, and pricked out 

 from a pouch beneath the first five of the dorsal arcs of the 

 abdomen, when they will be seen to be not sessile, but attached 

 to a muscular arm about two inches long, and have their hair 

 pencils where they lay in the fold opposite the fourth segment 

 stained by a deep saturation revealing the position of the 

 secretory glands (Plate IV., Fig. 9,/; Plate V., Fig. 8, x). The 

 nature of this emanation, however, varies, as may be seen by 

 procuring in summer some of the pot-herb kinds that repose on 

 our garden palings. In the abundant grey Cabbage Moth the 

 fans will be found to be orange, and flavouring of vinegar; 

 in the Dark Arches they smack of turpentine, and make us 

 think of the deal boards whence we have dislodged this heavy- 

 looking cornice-sleeper ; and in the evening Wainscot Moth of 

 flower i:)lots they are said to be redolent of ratafia ; but in the 

 male of the Angle Shades they, on the contrary, are black, 

 although the secretion does not differ from that we observe in the 

 Cabbage Moth. In the autumnal Red Underwing Moth of 

 willowed canals and poplar clumps the position of the fans is 

 quite different, for they are found on the legs at the upper part 

 of the second pair of tibiae, which are grooved for their reception 

 (Plate v.. Fig. 9, A. B.). 



In the Erebidae, a family remarkable for including the 

 Great Owl Moths of South America, and which, like the Atlas 

 Beetles, have but one representative assigned them in Europe, the 

 heavy fans are likewise on the hind tibiae of the males, and 

 one bi'ownish species takes its name after their odour, so we 

 often find them situated in the great family produced from 

 looping caterpillars, which includes genera that approach these 

 capacious wings in form. Bat in other kinds of Geometrina we 

 may find the scent organs on the alar trachea? as in their proto- 

 types the butterflies, and here they occupy a position on the 

 submedian vein of the forewing (Plate V., Fig. 5). Their 

 secretion is orange, smacking of turpentine and vinegar, or of a 

 white colour. In Herminia, a genus of Pyralidina, including 



