Moths. 129 



tube with which they are provided which opens at the 

 surface of the water. Some of these insects are very 

 destructive to vegetation ; the larvae of the common 

 daddy-longlegs for instance, feeds on the roots of grass 

 and will thus sometimes destroy large patches of 

 meadow. The Hessian fly is still more formidable, 

 often destroying whole fields of wheat by attacking 

 the young plants before they are in flower. 



ORDER XI. Lepidoptera, is also a large order, 

 and includes those most beautiful of all insects, the but- 

 terflies, characterised by possessing four wings covered 

 with fine dust-like scales. These microscopic scales 

 overlap each other on the surface of the wings, and are 

 of different shapes in different species. Butterflies have 

 suctorial mouths (fig. 67), the proboscis-like sucker 

 being rolled up when not in use. The larvas or cater- 

 pillars consist of thirteen joints and are very unlike in 

 mouth, structure, and general appearance to the perfect 

 forms which emerge from them. 



On the lower lip in the larvae of some moths there 

 is the outlet of two spinning glands, which when the 

 larva has reached its full size secrete the material for 

 a silken cocoon within which it is enclosed in the pupa 

 state. 



These insects vary in size ; some, as the clothes 

 moths and fur moths, are very small. 



The larvae of the leaf-rollers, a form nearly allied 

 to the clothes-moth, roll up the leaves of plants on 

 which they feed into tubes, within which they live and 

 pass their pupa sleep, and whence they emerge in 

 due time as little broad-winged moths. 



Another related form often found on apple trees is 



