48 COMMON BRITISH INSECTS. 



Not only the Beetles, but their larvae inhabit the 

 water, and they are equally predacious in both stages 

 of existence, the larva being armed with a pair of 

 enormous sickle-shaped jaws. They are all long and 

 narrow, and have six minute eyes, or ocelli, at each 

 side of the head. We will now proceed to our ex- 

 amples of these insects. 



THE Hydradephaga are divided into two families, 

 the Dyticidae and the Gyrinidae. There is not the 

 least difficulty in deciding the family to which any 

 Water Beetle belongs, as a glance at the antennae is 

 sufficient for the purpose. The antennae of the 

 Dyticidae are long and slender, and those of the 

 Gyrinidae are stout, short, and club-like. Moreover, 

 the first pair of legs are short in the Dyticidae and 

 long in the Gyrinidae. We begin with the first family, 

 and take an example of the typical genus. 



The GREAT WATER BEETLE (Dyticus margi- 

 nalis] may be found plentifully in almost any pond, 

 lake, or slow stream ; either resting with head down- 

 wards, or propelling itself with its powerful hind 

 legs. The sexes of this and other species are so 

 distinct that in the earlier days of entomology 

 they were looked upon as different species. As 

 the habits of this Beetle are almost identical with 

 those of all its family, it will be described at 

 greater length than can be afforded to the generality 

 of insects. 



If one of these Beetles be examined on the under 

 side, the metasternum will be seen to have a forked 

 and rather sharp projection from its centre, the points 



