264 LIFE STORIES OF AUSTRALIAN INSECTS 



It is interesting to note that all water beetles have 

 a general smooth appearance, narrowing at the sides 

 to enable them to cut through the water. Some 

 have longitudinat grooves, but the general surface 

 of such beetles is smooth. 



These beetles have to take down a supply of air. 

 To do this a beetle rises to the surface of the water 

 and protrudes the tip of the abdomen. It raises the 

 elytra and draws in a supply of air into a cavity 

 between the elytra and the back of the beetle. 



These beetles can fly long distances from pool 

 to pool. The eggs are laid on water plants. 

 The female cuts a slit and inserts an egg in 

 each slit. The larva (Plate 33, Fig. 1) hatches 

 out and feeds on small insects and young 

 tadpoles. It is very voracious, and is called a 

 '* water- tiger." It has large mandibles, which are 

 hollow, and are capable of seizing and piercing the 

 victim and then sucking the juices of the body. The 

 mouth proper is small. At the end of its body are 

 fringes of hair (Plate 33, Fig. 1, a), and these aid 

 it in its movements in the water and also help it to- 

 float to the surface when it needs an air supply. The 

 air is taken in by the two enlarged terminal spiracles 

 only. 



The dytiscid larva has curious eye-plates on which 

 we found six single eyes arranged in three pairs 

 (Plate 33, Fig. 1, b). 



Family Hydrophilidae (Plate 33, Figs. 5 and 6) 

 lazy water beetles. These are so called because they 

 are neither so active nor so fierce as the dytiscids 

 or gyrinids. They are mostly vegetable feeders, 

 are really water scavengers feeding on decaying 



