262 LIFE STORIES OF AUSTRALIAN INSECTS. 



down a supply of air, which can be seen at the 

 end of the body as a beautiful glistening silver 

 ball; they do not stay long under water. These 

 beetles are carnivorous, and feed on any water 

 creatures they can capture. They also seize any 

 flying insect which may fall into the water. 



The larva (Plate 33, Fig. 2) lives in the water 

 and does not need to come to the surface to get an 

 air supply. It has plate-like projections or gills at 

 the sides of the body which help it to move about in 

 the water, and also aid in the breathing of the larva. 

 The metathorax carries the two main breathing 

 spiracles. The eggs are small and cylindrical, placed 

 in parallel rows on leaves of aquatic plants. The 

 larva pupates on water plants. 



II. Family Dytiscidse or Diver Beetles (Plate 

 o3, Fig. 1, a, b, c, and d). 



(a) The antennae are filiform or thread-like; (b) 

 There is only one pair of eyes; (c) The back legs 

 are long and like a pair of oars; they are widely 

 separated from the middle pair because of the large 

 coxse or thighs of the hind legs which cover the 

 greater part of the thorax. They are the main 

 organs of locomotion and are clothed with collapsi- 

 ble hairs on the lower part of the leg ; the hairs al- 

 ternately spread out and then collapse; (d) The tip 

 of the abdomen is not exposed. A common genus 

 is Cybister. (Plate 33, Fig. 1, d.) 



Habits. These beetles are predaceous, and 

 very fierce ; they will attack other water creatures 

 The elytra are smooth and curved tightly round 

 the body, except at the tip of the abdomen. The 

 elytra thus cover well the flying wings and spiracles, 



