330 



BIONOMICS, ETC. 



[CH. 



usually leave the ground. Lizards and snakes are, curiously enough, 

 expert at catching Dragonflies. I once 

 saw Diphlebia lestoides alight upon 

 the tail of a lizard which was sunning 

 itself on a rock. The lizard caught 

 it, by a stroke as quick as lightning ! 

 Birds frequently attack Dragonflies ; 

 but, as far as my observations go, 

 seldom succeed in catching them. 

 The kingfishers are an exception, as 

 they are wonderfully expert at catch- 

 ing Dragonflies skimming close to the 

 water. The most deadly enemy of all 

 is the trout. In Tasmania, the intro- 

 duction of the English trout has 

 reduced the Odonate fauna of the 

 rivers to a minimum. A 2-lb. trout 

 which I caught on the Macquarie 

 River in Tasmania had in its stomach 

 the undigested heads of thirty-five 

 Dragonflies, twenty-eight belonging to 

 the rather rare species Procordulia 

 jacksoniensis. There were also the 

 remains of one beetle. 



The trout is also an enemy of the larvae, especially of those 

 Libellulidae which live on the bottom of slowly moving rivers. 

 The voracious larva of the beetle Dytiscus frequently attacks 

 Dragonfly larvae. But the latter has no enemy to compare with 

 his own near relatives, if they happen to be of a somewhat larger 

 size. 



Parasites (figs. 168, 169). 



These may be divided into true parasites and false parasites. 

 Of the former, the best known are the tiny Hymenoptera of 

 the families Tetragrammidae and Mymaridae, or "fairy flies." 

 Three species (Anagrus incarnatus, Polynema ovulorum and P. 

 natans) have been described as laying their eggs within the eggs 

 of Calopteryx. The grub hatches out and feeds on the contents 



Fig. 167. Austrolesles analis 

 Ramb., <?, and a number of 

 smaller insects, captured by 

 Drosera binata Labill. ( x ). 

 Original drawing by P. Tillyard. 



