MOTHS 83 



herbage, and attracts the female by an odour given off 

 by dense tufts of long hairs on the tibiae of the hind- 

 legs. The wing-colour of the female is ochreous 

 yellow, and there can be little doubt that this dis- 

 similarity of the sexes is due to natural selection the 

 whitest males in each generation being most likely to 

 mate, since they are most readily seen by the females. 

 This view is supported by the fact that in Shetland, 

 where the summer nights are very light, the male is 

 often yellow like the female. 



In members of the family Zyganida we find, for the 

 first time, a frenulum at the base of the hind-wing, 

 and the proboscis is well developed. There are two 

 genera viz., the burnets, 1 and the foresters, 2 all the 

 species flying by day, preferably in sunshine. The 

 typical larva of the family is short and stout. Before 

 changing to the pupa, it spins a strong, elongate 

 cocoon on a stem of grass or some other plant. 



In the family Psychidce the caterpillar constructs a 

 silken case covered with fragments of stick or refuse. 

 The adult female is grub-like in form, and wholly 

 helpless. She never leaves her case, but is visited 

 therein by the male, which has well-developed wings, 

 and flies with considerable strength and swiftness, 

 usually by day. We have only three British species. 

 The clearwings 3 make up another family of day- 

 flying moths, whose larvae feed in wood, or in the 

 rootstocks or stems of plants, the commonest being 

 that of the currant-clearwing, which burrows in the 

 twigs of currant bushes and destroys the pith. The 

 adult moth* appears in June, and is common in most 

 gardens, where it frequents flowers of various kinds. 



1 Zyg&na. 2 Procris ; Ino of some authors. 



3 SesiidoB. 4 Sesia tipuliformis. 



