XVII] BIONOMICS, ETC. 329 



all tightly packed into a black mass. I have frequently seen 

 Aeschna brevistyla take gnats and mosquitoes in dozens, while on 

 the wing. There can be no doubt that those Dragonflies which 

 fly late in the day are of great value in checking the spread of the 

 various objectionable Culicidae that are on the wing from just 

 before sundown. 



The largest Dragonfly that I have ever seen captured was 

 Synlestes iveyersi, seized by Aeschna brevistyla while on the wing. 

 The wings were quickly bitten off, and fluttered to the ground. 

 The whole of the long body was chewed up in a few minutes, but 

 the thorax was mostly discarded. 



As regards Dragonfly larvae, they seem to relish almost anything 

 they can catch, but more particularly smaller specimens of their 

 own or other species of Odonata. When young, they feed readily 

 on Protozoa. A little later, they are expert at catching water-fleas 

 and other small Crustacea. Later on, I find they prefer the larvae 

 of May-flies or mosquitoes to anything else. As an experiment, 

 I once kept a larva of Synthemis macrostigma without food for 

 a week. I then offered it mosquito larvae in large numbers. 

 It used its mask with such vigour that I counted no less than 

 sixty larvae swallowed within ten minutes. After that, nothing 

 would tempt it. As regards the large Aeschnine larvae, I find 

 that they will stalk Agrionid or Lestid larvae with persistency 

 and cunning. They will also stalk one another, and woe be to 

 the one that is in front! They also attack tadpoles and even 

 small fish, but always refuse to eat more than a small portion of 

 them. 



Enemies. 



In the imaginal state, the Dragonfly has a number of enemies, 

 most of which can, however, only compass his destruction if 

 they come upon him just after metamorphosis, before his wings 

 are ready for flight. Amongst the plants, the giant sun-dew 

 (Drosera binata) takes heavy toll of those Australian Zygoptera 

 which frequent swamps and marshes (fig. 167). Spiders prey 

 upon Dragonflies, both by capturing them in their webs, and by 

 pouncing upon them at metamorphosis [196]. Gomphinae appear 

 particularly liable to attack at this latter time, since they do not 



