86 POPULAE ENTOMOLOGY. 



supper-table with a mask of this construction, and serving 

 themselves by its assistance : these creatures steal upon 

 their prey as a cat does on a mouse." They live in the 

 water for ten or eleven months prior to their final change, 

 and from spring until the commencement of autumn may 

 be seen in every favourable locality ; when ready to quit the 

 pupa state they leave the water, and, ascending the stem 

 of some aquatic plant, allow their outward covering to become 

 dry and brittle, when it splits down the back, and the head 

 and legs make their appearance. The insect then seizes a 

 twig with its fore legs, and draws out the rest of the body ; 

 after which it remains a considerable time, until its wings 

 acquire their full size and gauze-like appearance. 



There are two families of Water Beetles seen this month, 

 and frequently earlier, — the Dyticida and Gi/rinidce, — the 

 latter remarkable for the metallic brilliancy of their cover- 

 ing, which distinguishes them from the Byticidm, The 

 velocity with which they execute their evolutions on the 

 surface of the water is truly surpising, and has obtained for 

 them the name of " Whirhgigs." One of our naturalists 

 thus describes them : — " Water — quiet, still water — affords 

 a place of action to a very amusing little fellow, Gyrinus 

 natatoTj which about the middle of April we see gambolling 



