XI. INSECTA. 39 



Diptera, or true Flies, have only a single pair of fully 

 developed wings, the hinder pair existing as minute rudimentary 

 organs, called ''halteres,''- or "poisers." The thorax Is highly 

 developed and is usually more or less globular. The transforma- 

 tions are complete. The mosquitoes, or true gnats, belong to this 

 group, and are only too well-known on account of the blood-sucking 

 haljits of the females, for, strange to say, it is this sex alone 

 which feeds upon the blood of animals, and produces the hum- 

 ming or trumpeting noise, which so often disturbs us at night. 

 The Tipulidce, or Crane-flies, the Mycetophilidce, or Fungus-gnats, 

 the Cecidomyidce, or Gall-gnats, the Tabanidce, or Breeze-flies, the 

 BomhyliidcB, or Humble-bee flies, and the Muscidce (including the 

 common House-fly and Blow-fly), are the most important families 

 of this order. Certain species of the parasitic family Hippohoscidce 

 are found on our domestic animals, and are often very troublesome. 

 The so-called sheep-tick, Melophagus ovinus (not to be confounded 

 with the true ticks with eight legs, which belong to the Arachnida, 

 an entirely different class), is a familiar example ; it is very flat, 

 has no wings, and has the body much widened behind. 



Aphaniptera include those insects, which in warm couutiies 

 are at times only too familiar, the Fleas ; these creatures feed 

 upon the blood of warm-blooded animals, and, in most cases 

 each species of flea attaches itself to some particular animal. 

 In Australia we have some very curious species, notably two, 

 which are found on the Porcupine Ant-eater (Echidna liystrix), 

 one a gigantic species, P. echidnce. Den,, and the other a very 

 remarkable form, Echidaophaga amhulans, OIL, which appears to 

 have lost the power of jumping. 



Rhynchota, or Hemiptera (Plant-bugs, Water-bugs, (fcc), 

 have a mouth formed for sucking, a large prothorax, and irregu- 

 larly veined wings; the fore-wings are often partly opaque and 

 coriaceous. The transformations are incomplete. The order was 

 divided by Latreille into two groups, the Heteroptera, or true 

 bugs, and the Homoptera^ the flrst containing a vast number of 

 species, many of them most brilliantly coloured. The Hydrocovisa^ 

 a group containing many species, are aquatic in their habits. 

 They are familiarly known as " water-scorpions" and "boatmen". A 

 gigantic species of this group, the Belostoma indicum, St. F. tk S., 



