THE EMPEROR MOTH. 97 
is in the month of August, and in the end of 
April they transform into the perfect fly. 
The Emperor Moth is not by any means rare in 
Britain, and is to be found in Kent, Sussex, Nor- 
folk, and Devonshire. 
The singular provision which Nature makes for 
the protection of this moth, deserves particular 
notice. When the time of its continuation in the 
caterpillar state is expired, by much labour it 
forms a kind of bag or purse of a very tough sub- 
stance. This it fixes against the trunks of trees, 
&e., by a number of hairs or filaments, which re- 
main on the external surface. It lines the outer 
case by one of a firm texture, the top of which is 
closed hy several bristles that unite in the centre, 
exactly representing a cap, and excludes almost the 
possibility of its receiving an injury during this 
defenceless state. In this bag it passes to the 
aurelia state, and remains until it transforms the 
perfect insect. 
Authors instance many plants as the food of the 
Emperor Moth ; it will live on the rose, the elm, 
alder, oak, the willow, and on thorns and brambles 
particularly. 
