248 



INTRODUCTION TO ZOOLOGY 



however, the beetle is put on his back out of water and then 



touched, he will put them out to cling with them ; the second 



pair also is hidden, except when the beetle is at rest, when 



they are extended in order to hold to the weeds ; the third 



pair is used exclusively for swimming. 



The male has, usually smooth elytra, but in the female 

 these are deeply furrowed their 

 whole length, and in the broad 

 furrows are hairs. When placed 

 on its back out of water, this 

 beetle will, if on a rough surface, 

 spring up and over on to its feet 

 with the greatest ease, and some- 

 times with a curious "sizzing" 

 noise. The larva is like that of 

 Dyticus but smaller, and with a 

 narrow first thoracic segment 

 looking like a neck. 

 „ . , A minute water 



' beetle often noticed 

 because of its almost globular 

 form and rusty red colour, is 



the Hyphydrus ovatus, with a body ^ of an inch long or less. 

 llybius is a beetle common round London and 

 in many other places. llybius ater is the commonest 



species ; it can be recognised by its 



black narrow body, convex above, 



and with a brownish-yellow streak 



down the outer margins of the 



elytra (see Fig. 176). 

 Pelobius. The Screech Beetle, 



The Screech or Squeaker {Pelobius 

 Beetle. Hermanni), is another 



common frequenter of ponds (Fig. 



177). It is about half an inch 



long, and is well known because of 



the strange squeaking noise it makes by rubbing the hard rim 



of the last segment of the abdomen in a groove of the elytra. 



The beetle is a golden-brown colour (reddish when dead), and 



there is a brownish-black patch over each eye, and along the 



front and back margins of the first thoracic segment, whilst a 



Fig. 175. — Hyphydrus ovatus. 



A, Resting at the bottom of the pond ; 



B, swimming down in the water. 



llybius. 



Fig. 



176 — llybius ater (the 

 ■'Mud-dweller"). 



