78 Key to Families of North American Insects. 



bugs. (Lygus [L. pratensis. Tarnished plant bug], Halticus, Poecilocapsus) 



(PI. 14, fig. 325.). (CAPSID.E.) MIRID^ 



Ocelli present; tarsi three-jointed 14 



14. Beak four-jointed; head vertical; membrane with one or two cells or one vein. 



(Isometopus.) ISOMETOPIDiE 



Beak three-jointed; head horizontal; membrane with four to one longitudinal 

 veins which are rarely entirely lacking. (Anthocoris, Triphleps [T. insid- 

 iosus. Predatory flower-bug]) (PI. 14, fig. 337) ANTHOCORIDiE 



15. Claws subapical; hind coxie distant; hemelytra of uniform texture, the clavus, 



corium and membrane confluent 16 



Claws apical 17 



16. Beak four-jointed, but the first joint short ; middle and hind legs close together, 



distant from the front ones and much longer than the latter. 



Water striders. (Gerris {= Limnotrechus)) (PI. 14, fig. 327) HYDRO- 



BATIDM GERRID^ 



Beak three-jointed; middle legs almost as distant from the front as from the 

 hind ones. (Microvelia, Rhagovelia.) VELIIDiE 



17. Prosternum without a stridulation groove IS 



Prostemum with a median stridulation groove; beak three-jointed, short and 



stout 25 



18. Ocelli absent; beak three-jointed 1& 



Ocelli present, when very rarely absent, the beak is four-jointed and the 



head is not apically widened 22 



19. Tarsi three- or four-jointed 20 



Tarsi two-jointed; broad, flat species living under bark; head produced between 



antennje; abdomen broader than the wings 21 



20. Body linear; head horizontal, as long as the thorax and widened toward the 



apex. Marsh treaders. (Hydrometra {= Limnobates)) (PI. 14, fig. 326). 



{LIMNOBA TID.E) HYDROMETRID.S 



Body oblong; head broad, triangular, shorter than thorax; eyes absent; no 

 scutellum; hemelytra short, destitute of membrane; parasitic on bats. 

 (Hesperoctenes) (PI. 14, fig. 333) POLYCTENID^ 



21. Head not wide behind the eyes which are prominent; beak longer than the 



head; trochanters very short, fusing with the femora; abdominal spiracles 

 placed near the base of the segments. (Aradus) (PI. 14, fig. 335). 



ARADID^ 



Posterior part of head wide, enclosing the eyes, often spinose, beak rarely 



longer than the head; trochanters distinct; abdominal spiracles remote 



from the base of the segments. (Aneiirus, Mezira.) DYSODIIDjE 



22. Beak four-jointed, with the first joint small; last joints of the antenn.ie more 



slender; membrane with two or three longitudinal cells emitting radiating 



veins. (Reduviolus, Pagasa.) NABID.^ 



Beak three-jointed 23 



