74 THE BUTTERFLY VIVARIUM. 



and other similar substances, which form their food, 

 while the other parts of the body are soft, to en- 

 able them to bend to the forms of the foliage or 

 branches to which they adhere. In the larvae of 

 Dipt era, however, which are almost invariably aqua- 

 tic, and take liquid food, great strength in the frame 

 of the head becomes unnecessary, and it is found in 

 most instances to be only membranous. In some 

 Dipterous larvae the head is indeed elastic, and can 

 be put in any form which the position of the insect 

 while feeding may require. Some of the Beetle 

 larvae have the power of withdrawing the head 

 nearly within the first segment of the trunk ; and 

 that of a small Gnat, Leminobea Replicata, has the 

 power of drawing in its head so completely tbat it 

 has in that state qxiite the appearance of a headless 

 body. In some Caterpillars the diameter of the 

 head is the same as the body ; in a few cases it is 

 larger, but in the greater number somewhat smaller. 

 The head in the larvae of Lepidopterous insects 

 is generally composed of two lobes, round at the 

 top, and dividing as they descend so as to leave a 

 triangle, within which are arranged the mandibles 

 and other features of the eating apparatus. In some 

 instances, however, as in the case of the Caterpillar 

 of the Purple Emperor, and a few others, the lobes, 



