18 Key to Families of North American Insects. 



ORDER MALLOPHAGA. 



(LIPOPTERA.) 



Small wingless insects averaging two mm. and very rarely over 

 five mm. in length. Body oval, or elongate, very strongly flattened; 

 usually strongly chitinized and generally with a conspicuous color 

 pattern of pale or yellowish markings contrasting with spots or 

 bands of dark brown or black. Mouth anterior, mandibles 

 strong, antennae three- to five-jointed; prothorax free; legs short, 

 no cerci. Metamorphosis very incomplete. External parasites 

 of birds, more rarely of mammals during entire life, feeding on 

 feathers, fur or skin. (Bird Lice, Biting Lice.) 



1. Antennae filamentous, exposed, three- or five-jointed; maxillary palpi absent; 



mandibles vertical; meso- and metathoracic segments usually fused. 



Suborder ISCHNOCERA 2 



Antennae clavate or capitate, concealed, four-jointed; maxillary palpi four- 

 jointed; mandibles horizontal; meso- and metathoracic segments with a 

 sutural line usually visible. Suborder AMBLYCERA 3 



2. Antennae three-jointed; tarsi with a single claw; infesting mammals. (Trichodectes 



[T. latus, Dog Louse].) TRICHODECTIIXE 



Antennas five-jointed; tarsi with two claws; infesting birds. (Docophorus, 

 Nirmus, Lipeurus.) (PL 2, figs. 34, 35.) PHILOPTERIDjE 



3. Tarsi with a single claw; infesting mammals. (Gyropus.) . . . GYROPODHLE 

 Tarsi with two claws; infesting birds (except in a few cases). (Menopon, 



Trindton.) LIOTHEID^ 



ORDER SIPHUNCULATA. 



(ANOPLURA, PSEUDORHYNCHOTA, PARASITA, PHTHIRAPTERA, 

 ELLIPOPTERA.) 



Small, more or less flattened, wingless parasites of mammals. 

 Head free, horizontal; eyes reduced or absent; mouth anterior, 

 comprising an unjoin ted, fleshy beak; antennae short; thorax 

 fused; legs similar; tarsi single-jointed, forming a claw at the end 

 of the tibia; no cerci; metamorphosis very slight. True lice. 



1. Body flattened; spiracles only at each side of the mesothorax and on abdominal 

 segments three to eight; antennae three- or five-jointed; tibia with a thorn- 

 shaped projection 2 



Body thick and stout; mesothorax and metathorax each with a pair of spiracles 

 as well as abdominal segments two to eight; eyes absent; tibia with a stout, 

 short, thorn-like projection; antennae four- or five-jointed; entire body sup- 

 plied with thorn-like bristles. (Echinophthirius.) . . ECHINOPHTHIRinXffi 



