352 



TRANSFORMATIONS OF INSECTS. 



the bottom of the water, and shed their skins several times, and 

 undergo their first metamorphosis during the spring. The fly does 

 not make much use of its wings during the day, but is Hvely in 

 the evening, and the females carry their bag of eggs suspended 

 to their bodies. Some of the species are found in high northern 

 latitudes, and appear over the snow at the very first approach of 

 spring. Pcida viarginata, whose aquatic and perfect conditions 

 are shown in the accompanying engraving, has two long articu- 



THE METAMORPHOSES OF Perla vmrgijicto,. 



lated processes, something like those of the earwig. It is a 

 common insect, and its larva, which is of a yellow citron colour 

 spotted with black, is found in running streams and swiftly- 

 flowing brooks. A closely allied species, the Nemoura, lives 

 exactly in the same way as the Pcrla, but they are smaller 

 insects. When young they have curious processes sticking out 

 from the body, like those of the Pcrla;, but they disappear in 

 the perfect insect. The wings are always perfectly developed 

 in the females, but they are short and rudimentary in the males. 



