486 THE MARGINED WATER BEETLE. 



OF THE ELATEB, OR SKIPPER TRIBE. 



THE Elaters fly with great facility, and when thrown upon their 

 backs, they are able to recover their position without using their feet : 

 for this purpose the thorax terminates in a strong 

 elastic spine, which is placed in a cavity of the 

 abdomen. The insects, when upon their back, 

 raise up the middle part of their body, so as to 

 leave only the head and tail in contact with the 

 plane on which they lie. The spine of the thorax 

 is by this motion brought considerably out of its lodgment, and made 

 to press against the side. Being from this position again slipped into 

 its groove, with all the force the creatures are able to exert, the thorax 

 and abdomen come together with so sudden a jerk, as to raise the 

 body from the plane, and enable them to spring round. 



The larvae live and undergo their changes in the trunks of decayed 

 trees. 



OF THE DYTISCUS, OR WATER BEETLE TRIBE 



THE bodies of these insects are admirably formed for passing 

 through the water with as little impediment as possible, being nearly 

 boat-shaped, and on the surface perfectly smooth. They inhabit ponds 

 and ditches, but occasionally fly in search of other waters. The 

 males are distinguished from the females, by having a horny concave 

 flap or shield on the forelegs. The hind legs in both sexes are pecu 

 liarly adapted for the aquatic residence of the insects, being fur- 

 nished on the inner sides with a series of long and close-set filaments, 

 so as somewhat to resemble fins. In the large species, the elytra or 

 wing-cases of the males are smooth, and those of the females furrowed. 



The larvae are extremely voracious, feeding on other aquatic in- 

 sects, on worms, and even on young fish. They continue in this state 

 about two years and a half ; and when about to change into pupce, 

 they form a convenient cell, and secrete themselves for the purpose in 

 the banks or amongst the weeds. 



THE MARGINED WATER BEETLE. 



Although water is the principal element in which these insects reside, 

 they are perfectly amphibious. They may occasionally be found in 

 all fresh waters; but are most frequently seen either in such as are 

 stagnant, or where the stream is extremely low. 



They are predatory and very voracious, devouring, in great num- 

 bers, not only other water-insects, but also those of the land. They 

 seize their prey in their forelegs, and with these carry it to the mouth 



