90 BRITISH INSECTS 



pillars of hawk-moths have ten prolegs, and (in all the 

 British species) a spine, or " tail," on the last segment. 

 The full-fed caterpillar burrows into the soil, and by 

 working itself round and round, forms a cell, wherein 

 it changes to the pupa. 



Two other British moths call for notice : First, the 

 emperor, 1 which is the sole British representative of 

 ts family, the Satiwniidce ; second, the Kentish glory, 2 

 which constitutes a family in itself, since it stands 

 remote from all other known Lepidoptera. Super- 

 ficially, these two species do not seem very dissimilar. 

 In both the proboscis is rudimentary, and the frenulum 

 absent ; but the number and arrangement of the ner- 

 vures in the wings characters upon which systematic 

 entomologists rightly lay great stress differ greatly, 

 and indicate two perfectly distinct lines of descent. 

 The handsome caterpillar of the emperor-moth is not 

 uncommon during July and August upon heath, birch, 

 and other plants. When full grown, it spins a dense, 

 pear-shaped cocoon, from which the imago emerges in 

 May of the following year. The Kentish glory, though 

 widely distributed in Britain as far north as the 

 Caledonian Canal, occurs only in certain favoured 

 localities. Its caterpillars, which feed on birch, re- 

 semble those of the hawk-moth family ; while the 

 pupa has the habit (very unusual among highly- 

 specialized moths) of working its way completely out 

 of its cocoon some days prior to the emergence of the 

 moth. Both the emperor and the Kentish glory are 

 examples of the phenomenon known as " sex-dimor- 

 phism " i.e., the coloration of the male is very dif- 

 ferent from that of the female. 



The remaining families of Lepidoptera comprise the 

 41 butterflies." In all the species the proboscis is de- 

 1 Saturnia pavonia. 2 Endromis versicolora. 



