144 INSKCTS OR HEXAPODA. 



morphosis. Those with biting mouth are called Man'lihulata ; 

 those with sucking and piercing mouths, Haustellata. Man- 

 dibulata include the Beetles, Grasshoppers, Cockroaches, Ants, 

 Bees, and "Wasps. The Butterflies and ]Moths, Flies, Bugs, 

 and Plant Lice are Haustellata. This arrangement is not at 

 all satisfactory, as we get insects in each with a complete and 

 incomplete metamorphosis. All insects may now be grouped 

 in nine orders, as follows : — 



1. Coleoptera, or Beetles. 



2. Hymennptera, or Ants, Bees, Wasps, Sawflies, &c. 



3. Lepidoptei'a, or Butterflies and Moths. 



4. Diptem, or True Flies. 

 .5. Thysanoptera, or Thrips. 



6. Hem.iptera, or Bugs and Plant Lice. 



7. Orfhoptera, or Cockroaches and Grasshoppers. 



8. Neuroptera, or Lace-wing and Caddis Flies. 



9. Aptera, or Thysanura and CoUembola ( = Spring-tails, itc.) 

 The first four orders undergo a complete, the next four an 



incomplete, metamorphosis. These orders may be distinguished 

 by the following characters : — 



Complete metamorphosis : — 



Ooleoptera — Two pairs of wings, first pair liorny {elytra). Mandibulate. 

 Hymenoptera — Two pairs of wings, all of similar texture, first with a 



dark stigma along the costa. Itandibulate and haustellate. 

 Lepidoptera — Two pairs of wings covered more or less with scales. 



Haustellate. 

 Diptera—One pair of wings only (the first pair). Haustellate. 



Incomplete or gradual metamorphosis : — 



Thysanoptera — Four narrow fringed wings. Weak suctorial mouth. 

 Hemiptera — Two pairs of wings, either (i) all transparent, or (ii) the first 



pair half leathery at the base and transparent at tip (hemielytra). 



Haustellate. 

 Orthopterii — First pair of wings leathery, with many longitudinal veins ; 



second pair fan-shaped. Jfandibulate. 

 Neuroptera — Two pairs of lace-like wings. Mandibulate. 



Scarcely any metamorphosis ;— 



Aptera — No wings at all. Mandibulate or slightly haustellate. 



