68 LIFE STORIES OF AUSTRALIAN INSECTS. 



numbers of mosquitoes, flies, etc.. so that they can 

 be regarded as friends to man even though they 

 incidentally may destroy some useful types. Dr. 

 Tillyard in "Biology of Dragon-flies," makes the 

 following observations on a dragon fly which he 

 saw ''flying round and round a small bush about 

 7 p.m., when the mosquitoes were particularly trou- 

 blesome. After ten minutes it was captured. 1 

 found its mouth so full of mosquitoes that it was 

 unable to shut it. There must have been over 

 a hundred mosquitoes all tightly packed into a 

 black mass." 



The head of the dragon-fly (Plate lo) is large 

 and very mobile ; the greater part is made up of 

 two large compound eyes, capable of a wide 

 vision. The eyes may meet on the top of 

 the head, especially in the males of certain species, 

 such as Aiia.v and other larger types. However, 

 there is an exception in the large mountain dragon- 

 fly, Petalura, where the eyes are not very large, and 

 are quite separated. The eyes of the Zygoptera 

 or damsel-flies are much smaller and more or less 

 stalked. 



The mouth is a biting and chewing type, and the 

 jaws are very powerful, but the arrangement of the 

 mouth parts is such that a dragon-fly cannot bite 

 one's finger in handling it. 



The wings are beautifully netted, the fore-wings 

 being slightly smaller than the hind pair. The 

 stronger dragon-flies are capable of very rapid flight 

 and the wing-structure is interesting, for there is 

 ^n area of strength which bears the main pressi^re 



