INTRODUCTION. 



sometimes lasting a very short time only ; in other insects many 

 months are spent at rest in this state. Then the sheath is split 

 and the insect emerges in its final form, and is known as an imago. 

 There is an exception to every rule — EphemeriAce emerge from the 

 pupal sheath as Sub-imagines or " Duns," and cast a further com- 

 plete sheath before they are known as Imagines or Spinners. 



This list has recently been overhauled. Entomology as a science 

 is unfortunately in a state of tentative development, and instead of 

 insects being entirely classified according to appearance and the 

 characteristics of their final development, they are now classified 

 according to various features of development during the earlier stages 

 of their existence, the idea followed being that all insects are in a 

 state of progressive development, and an attempt is now made to 

 arrange and classify according to their place in this development. 

 This is the general list of orders which is adopted at present : — 



Sub-Clziss. 

 Apterygota. — 



Wingless. 

 Exopierygota. — 



Wings 



developed 



visibly 



outside 



the cuticle. 



Class Hexapoda — or Insecta. 



Order. Type. 



Endopterygota. — 

 Wings deve- 

 loped beneath 

 the larval 

 cuticle only 

 visible after 

 penultimate 

 moult. 



1. Aptera 



2. Dermapiera 



3. Orihopiera 



4. Plecoptera 



5. Corrodentia 



6. Ephemeroptera 



7. Odonata 



8. Thysanoptera 



9. Hemiptera 



10. Anoplura 



11. Neuroptera 



12. Coleoptera 



13. Mecaptera 



14. Trichoptera 



15. Lepidopiera 



16. Diptera 



17. Siphonaptera 



18. Hymenoptera 



Silver-fish or Sugar-louse. 



Earwigs. 



Cockroaches, Grass Hoppers, 



Crickets, etc. 

 Stone Flies. 

 Book-lice, etc. 

 Mayflies. 

 Dragon-flies. 



Thrips or Flower Insects. 

 Bugs, Frog Hoppers,Aphides, etc. 

 Lice. 



Alder Fhes, Lacewings, etc. 

 Beetles. 

 Scorpion-flies. 

 Caddis Flies. 

 Butterflies and Moths. 

 Two-winged Fhes. 

 Fleas. 

 Ants, Bees, Wasps, etc. 



