57 



depopulated. When the tiger has reacned his full size, his form 

 changes and he rests for a time as a pupa and then comes forth as a 

 hard, shiny beetle like figure 13. 



The water-scavenger beetle (figure 15), so called because of his 

 appetite for decayed matter, is common in many ponds. It has, like 

 the diving beetle, a hard, 

 shiny back, with a straight 

 line down the middle, but 

 they can be distinguished 

 when seen together. The 



young of this beetle look ^ 



, . ,.- Fig. 14. — A xvater-tiger. 



somethmg like the "water- 

 tiger " but have not such great, ugly jaws. 



There are three other swimmers even more 

 delightful to watch than those already men- 

 tioned. The water-boatmen (figure 16), with 

 their sturdy oar-hke legs and business-like way 

 of using them, are droll little fellows. They 

 are not so large as the back-swimmers. Figure 

 17 shows a back-swimmer just in the act of 

 pulling a stroke. These creatures swim with 

 their boat-shaped backs down and their six 

 legs up. We must be careful how we handle 

 the back-swimmers, for they carry a sharp bill 

 and may give us a thrust with it which would 

 be painful. 



The water-scorpion (figure 18) is a queer 

 creature Hving in a neighborly way with the 

 boatmen and back-swimmers, though not so 

 easy to find. Do not throw away any dirty 

 little twig which you find in the net after a 

 dip among water plants near the bottom of a 

 stream or pond. It may begin to squirm and 

 reveal the fact that it is no twig but a slender- 

 legged insect with a spindle-shaped body. 

 We may handle it without danger, as it is 



harmless. This is a water-scorpion, and his way of catching his prey 

 and getting his air supply will be interesting to watch. He is not shy 



Fig. 15. — A water-scav 

 enger beetle. 



Fig. 16. — Water-boatman. 



