264 COMMON BRITISH INSECTS. 



When full-fed the larva makes a slight cocoon, and 

 therein undergoes its transformations. 



Now we come to a very extraordinary creature. 



There is one family of Moths, comprising only 

 four species, the larvae of which are dwellers in the 

 water, thus trespassing on the domains of other orders 

 of insects. This is a group of Moths popularly 

 called China Marks, because the general character of 

 the surface of the wing and its markings has very 

 much of a porcelain character about it. The typical 

 species is Hydrocampa stagnalis. In all these Moths, 

 the female is considerably larger than the male, and 

 is rather variable in her colouring, so that the older 

 entomologists have in several cases considered the 

 sexes as forming distinct species. The male has no 

 feathering to the antennae, and the palpi are short, close 

 together, arid directed upwards. 



The Moths are pretty little creatures, but the chief 

 interest of the insect lies in the larva, which has a 

 mode of existence that seems quite opposed to the 

 whole character of the Lepidoptera. The caterpillars 

 feed upon aquatic plants, and in some species are 

 absolutely sub-aquatic themselves. It is evident that 

 the respiratory apparatus of such larvae cannot be 

 formed like that of ordinary caterpillars, which breathe 

 atmospheric air through spiracles and breathing tubes. 

 Accordingly, these larvae, like those of the caddis, the 

 May-flies, and one or two beetles, such as the whirli- 

 vvig, which has been described in the course of this 

 work, are furnished with gill-like filaments along their 

 sides, by means of which they extract the oxygen from 

 the water just as fishes do. 



