Key to Families of North American Insects. 



tarsal claws; pupal stage present. White-flics. (Aleyrodes [A. vaporario- 

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



ALEYRODID^ 

 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. hrassicoe. Cabbage 

 Aphid; A. goss;jpii. Melon Aphid; A. mali, Apple Aphid; A. sorbi. Rosy 

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

 odon [P hurtiidi. Hop Aphid], Nectarophora [A''. {=Macrosiphvm) pisi. 

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



APHIDID^ 



ORDER HEMIPTERA. 



(HETEROPTERA ; RHVNCHOTA, part.) 



Terrestrial or aquatic species ranging from minute to large sizej 

 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; prothorax 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 metastemum 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 



Antennae 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) ) {PELOGONIDJE) OCHTERID-^ 



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

 with prominent eyes. (Gelastocoris, Mon6n5rx.) 



(GALGULID^E, MONONYCHIDM) NERTHRID.S 



Cr C /4L6 to 



