10 Key to Families of North American Insects. 



43. Very small (three millimeters) louse-like jumping species; prothorax incon- 



spicuous. Book-lice CORRODENTIA (Page 17) 



Larger, or at least not louse-like species; prothorax large 44 



44. Hind legs fitted for jumping, the femora enlarged; wing-pads of larva? when 



present in inverse position, the metathoracic overlapping the mesothoracic 



ORTHOPTERA (Page 13) 



Hind legs not enlarged for jumping; wing-pads, if present, in normal posi- 

 tion 45 



45. Prothorax much longer than the mesothorax; front legs fitted for grasping 



prey MANTOIDEA (Page 16) 



Prothorax not greatly lengthened 46 



46. Cerci present; antennae usually with more than fifteen joints, often many- 



jointed 47 



No cerci; body often hard-shelled; antennas usually with eleven joints 



COLEOPTERA (Page 30) 



47. Cerci with more than three joints 48 



Cerci short, with one to three joints 49 



48. Body flattened and oval; head inflexed; prothorax oval. Roaches. 



BLATTOIDEA (Page 16) 

 Body elongate; head nearly horizontal; prothorax quadrate. 



GRYLLOBLATTOIDEA (Page 13) 



49. Tarsi five-jointed; body very slender and long. Walking-sticks 



PHASMOIDEA (Page 14) 

 Tarsi two- to four-jointed; body not linear 50 



50. Front tarsi not enlarged 51 



Front tarsi with the first joint swollen EMBKDINA (Page 42) 



51. Tarsi apparently four-jointed; cerci with several joints; antennae with nine to 



thirty joints ISOPTERA (Page 17) 



Tarsi two-jointed; cerci one-jointed; antennae nine-jointed; minute species 

 restricted to the East Indies ZORAPTERA (Page 17) 



52. Body cylindrical, caterpillar-like PANORPATAE (Page 46) 



Body more or less depressed, not caterpillar-like 53 



53. Mandibles united with the corresponding maxillae to form sucking jaws 



Larvae of Neuroptera 

 Mandibles almost always separate from the maxillae 



Larvae of Cole6ptera, Raphidioidea, Strepsiptera 



54. False legs numbering five pairs or less Larvae of Lepidoptera 



False legs numbering six to eight pairs 



Most larvae of suborder Chalastogastra, Hymenoptera 



55. Body bare or with few scattered hairs 56 



Body densely clothed with hairs or scales; proboscis if present coiled under the 



head. Moths LEPIDOPTERA (Page 48) 



56. Last tarsal joint swollen and with no claws; mouth consisting of a triangular 



unjointed beak; minute species. Thrips .... THYSANOPTERA (Page 15) 

 Tarsi not bladder-like at the tip, and with distinct claws 57 



