76 Key to Families of North American Insects. 



tarsal claws; pupal stage present. White-flies. (Aleyrddes [A. vaporario- 

 rum, Greenhouse white-fly], Aleurodicus) (PI. 16, figs. 369, 375). 



ALEYRODIIXflE 



Wings transparent, though sometimes colored; tarsi two-jointed, the basal 

 joint sometimes very much reduced; body not mealy but rarely with waxy 

 wool; process between the tarsal claws absent or nearly so. Plant-lice. 

 (Phylloxera [P. vasiatrix, Grape Phylloxera], Aphis [A. brassicae, Cabbage 

 Aphid; A. gossypii, Melon Aphid; A. mali, Apple Aphid; A. sorbi, Rosy 

 Aphid], Myzus [M. cerasi, Cherry Aphid; M. ribis, Currant Aphid], Phor- 

 odon [P humuli, Hop Aphid], Nectarophora [N. ( Macrosiphum) pisi, 

 Pea Aphid], Toxoptera [T. graminum, Grain Aphid]) (PL 16, figs. 373, 374). 



ORDER HEMIPTERA. 



(HETEROPTERA ; RH YNCHOTA, part.) 



Terrestrial or aquatic species ranging from minute to large size; 

 usually more or less flattened or cylindrical; feeding on the juices 

 of plants or animals. Head free, forming a sucking, inflexed, 

 jointed beak which is usually inserted toward the front end of 

 the head; antennae with few joints, those of the terrestrial species 

 usually long; pro thorax large, free; wings overlapping on the 

 abdomen, the fore pair (hemelytra) tough at the base and mem- 

 branous apically, the hind pair with large anal field, wings some- 

 times reduced or absent; legs of variable form, tarsi normally 

 three- jointed; no cerci. Metamorphosis incomplete. True 

 Bugs. 



1. Tarsal claws devoid of arolia, very rarely provided with arolia (Miridae) in 



which case the meso- and metasternum are composite 2 



Tarsal claws always provided with arolia; beak generally four-jointed; meso- 

 and metasterna simple 27 



2. Antennae very short; meso- and metasternum composite; metasternum devoid 



of gland openings; aquatic species 3 



Antennas always longer than the head, if slightly shorter, the eyes and ocelli 

 are absent 9- 



3. Ocelli present; beak four-jointed 4- 



Ocelli absent; antennae more or less hidden in cavities in the head; aquatic 



species 5 



4. Antennae exserted; front legs as long as the middle ones; formed for running. 



(Ochterus (= Pelogonus] ) (PELOGONIDsE) OCHTERIDJE 



Antennae hidden; the front legs formed for grasping; short and broad species 

 with prominent eyes. (Gelast6coris, Mononyx.) 



(GALGULID&, MONONYCHID&) NERTHRID^E 



