The Orders of Insects 163 



Order 7. Hemiptera (Bugs, Lice, Cicads, Plant-lice, &c.). — 

 Insects with piercing and sucking jaws, the needle-like 

 mandibles and first maxilla working within a tube formed by 

 the union of the second maxills ; no palps. Kidney-tubes 

 few. Metamorphosis none (Bugs, Lice), incomplete (Cicads), 

 or almost complete (male Scale-insects). 



Order 8. Plectoptera (Mayflies). — Insects with vestigial jaws, 

 delicate net-veined wings, the hind pair being much smaller 

 than the front pair, and long tail cercopods. Genital openings 

 paired, the ducts without chitinous lining. Kidney-tubes 

 many. Incomplete metamorphosis, the larva; aquatic with 

 tracheal gills ; a siib-imaginal stage before the final moult. 



Order 9. Odonata (Dragonflies). — Insects with short bristle-like 

 feelers, powerful biting jaws and four sub-equal net-veined 

 wings of glassy texture. Male genital armature on second 

 abdominal segment. Kidney-tubes many. Incomplete meta- 

 morphosis, the larvjE and nymphs aquatic. 



Order 10. Neuroptera (Alder-flies, Lacewing-flies, Scorpion- 

 flies). — Insects with prominent feelers, biting jaws, and four 

 similar net-veined wings. Kidney-tubes few. Complete 

 metamorphosis, larva: campodeiform, rarely cruciform. 



Order ii. Coleoptera (Beetles). — Insects with the prothorax free 

 and large ; forewings strongly chitinised, forming sheaths for 

 tlie membranous hindwings wiiich can be folded beneath them. 

 Mandibles well developed for biting. Kidney-tubes few. Com- 

 plete metamorphosis; larvje campodeiform or cruciform. 



Order 12. Trichoptera (Caddis-flies). — Insects with four hairy 

 wings, the forewings usually longer and narrower than the 

 hindwings. Mandibles present in pupa but absent in imago, 

 which has the two pairs of maxilla; partly fused to form an 

 imperfect sucking apparatus. Kidney-tubes few. Complete 

 metamorphosis ; the cruciform larvje are aquatic. 



Order 13. Lepidoptera (Motiis and Butterflies). — Insects with 

 four scaled wings. Mandibles absent or vestigial in imago, 

 very rarely present in pupa. First maxilla; with galea; much 

 lengthened and grooved, forming when united a perfect 

 sucking tube ; palps rarely, lacinis very rarely present. 

 Kidney-tubes few. Complete metamorphosis ; the larvE are 

 cruciform (caterpillars) with three pairs of thoracic legs and 

 two to five pairs of abdominal prolegs. 



Order 14. Diptera (Flies and Fleas). — Insects with the forewings 

 developed (rarely wanting) and the hindwings reduced to 

 stalked knobs. Mandibles and blades of first maxilla;, if 

 present, adapted for piercing ; hoods of second (?) maxills for 

 sucking. Kidney-tubes few. Complete metamorphosis ; larvje 

 cruciform. 



