122 INSECT ARTIZANS AND THEIR WORK 



of those whose life-history is known in detail are 

 larvas for nearly two years. They make straight 

 vertical shafts in the stems or roots. One of the 

 best known of the group is the Currant Clearwing 

 (Sesia tipuliformis), which bores out the centre of 

 black and red currant stems, entering above and 

 working towards the base of the stem. Just before 

 the emergence of the moth the chrysalis works its 

 way through the thin skin-like bark, and sticks 

 out some distance. 



One of the largest of this group is the Lunar 

 Hornet Clearwing (Trocbilium crabroniformis) , which 

 is not like a hornet, as its names indicate, but very 

 like a wasp when the insects are seen apart. Its 

 caterpillar mines in the stems of willow, sallow, and 

 poplar. Before becoming a chrysalis the cater- 

 pillar prepares for the egress of the moth by carving 

 a way out to the air and spins a cap for the exit 

 in which it so artfully mixes up some fragments 

 of the bark that the cavity can scarcely be detected 

 for what it is. 



The caterpillar of the Light Orange Underwing 

 (Brephos notba) becomes a carpenter only when it 

 has nearly reached the end of its existence as a 

 larva. Up till then it feeds upon leaves of aspen, 

 spinning two of them together to hide it from 

 public observation, but when it feels that its 

 feeding days are over it bores into the bark or the 

 sap-wood beneath, hiding its entrance by making 

 a cap similar to that of the Hornet Clearwing, 

 and then changes into a chrysalis. The moth has 



