Key to the Orders of Insects. 1 1 



57. Prothorax distinct 58 



Prothorax small, hidden when viewed from above DIPTERA (Page 61) 



58. Beak arising from the front part of the head. . . .HEMIPTERA (Page 76) 

 Beak arising from the back part of the head. . . .HOMOPTERA (Page 73) 



59. Mouth mandibulate 60 



Mouth haustellate, forming a strong pointed inflexed beak 



Nymphs of Hemiptera 



60. Body not encased in a shell made of sand, pebbles, leaves, etc 61 



Case-bearing forms. Periwinkles Larvae of Trichoptera 



61. Abdomen furnished with external lateral gills or respiratory processes (a few 



Coleoptera here also) 62 



Abdomen without external gills 63 



62. Abdomen terminated by two or three long feathery gill-processes 



Larvae of Plectoptera 

 Abdomen with short end-processes Larvae of Megal6ptera 



63. Lower lip strong, extensile, and furnished with a pair of opposable hooks 



Larvae of Odonata 

 Lower lip not capable of being thrust forward and not hooked 64 



64. The three divisions of the thorax loosely united; antennae and caudal filaments 



long and slender Larvae of Plecoptera 



Thoracic divisions not constricted; antennae and caudal filaments short 



Larvae of Coleoptera 



65. Body flattened 66 



Body strongly compressed; mouth formed as a sharp inflexed beak; jumping 



species. Fleas SUCTORIA (Page 72) 



66. Mouthparts formed for biting (chewing) 67 



Mouthparts formed for piercing and sucking 68 



67. Mouth inferior; cerci long; African species parasitic on rodents 



DIPLOGLOSSATA (Page 14) 



Mouth anterior; no cerci; generally elongate-oval insects with somewhat tri- 

 angular head; parasites of birds or mammals. Biting-lice 



MALLOPHAGA (Page 18) 



68. Antennae exserted, visible, though rather short 69 



Antennae inserted in pits, not visible from above 



Pupiparous DIPTERA (Page 61) 



69. Beak unjointed; tarsi formed as a hook for grasping the hairs of the host; per- 



manent parasites. Lice SIPHUNCULATA (Page 18) 



Beak jointed; tarsi not hooked; temporary parasites 



HEMIPTERA (Page 76) 



70. Legless, grubs, maggots or borers; locomotion effected by a squirming motion. 



Larvae of some beetles, flies, moths, ants, bees and wasps. If living in the 

 body of wasps or bees, with the head exposed, compare the females of 

 Strepsiptera. 

 Sedentary forms, incapable of locomotion 71 



