CHAP, xix INSECTA: RHYNCOTA 277 



order, and hence the name Rhyncota seems a better one for 

 the entire group. In all members of this order the meta- 

 morphosis is gradual. The larva has a proboscis like that of 

 the adult, but is wingless. There is no quiescent pupal stage, 

 the wings developing gradually. 



The order is subdivided according to the 

 ' rs ' structure of the wings. The larger Water-bugs 

 form the sub-order Heteroptera, for in them the basal portions 

 of the fore-wings are horny, and the tips of these wings, as 

 well as the whole of the second pair, are membranous. The 

 wings fold flat on the back when at rest. 



The second sub-order, the Homoptera, consists of those in 

 which the two pairs of wings are alike and both membranous. 

 This sub-order includes the well-known garden pests, the 

 Green-fly (Aphis) and also the interesting Bark-lice (Chermes). 



Sub-order 1 : Heteroptera or Water-bugs. 



Series A. Aquatic forms living under water, and with the 

 antennae hidden on the under side of the head. 



Type 1 : The Water Scorpion (Nepa cinerea). 



The Water Scorpion is a form nearly always to be found 

 in any shallow piece of stagnant water. It is easily recog- 

 nised by its curious, flattened, dark-brownish body, which 

 looks rather like a fragment of a decaying leaf, and is often 

 difficult to detect, whether it is resting on the water surface 

 amongst the floating vegetation, or lying in wait for its prey 

 on the dark mud bottom of a pond. The difficulty of seeing 

 it is further increased by its extreme immobility it rarely 

 moves, and then but slowly. The wings are pressed flat on 

 the body and are seldom used (Fig. 204). 



To catch its food, which consists of small insect 

 larvae or of tadpoles, it uses its front pair of legs, 

 which project forward so that the last joints are brought to 

 the level of the mouth, where they spread out on either side. 

 These last joints are peculiar ; for the sharply pointed and 

 sharp-edged tarsus can be closed into the deep groove of the 

 preceding joint, like the blade of a clasp-knife into its handle ; 



