THE ASSASSIN BUGS. 537 



armed with spines; tarsi 3-jointed (1-jointed in Carthasinag) , 

 their claws terminal; osteola obscure or wanting. 



The family is one of the largest and most important of the 

 Heteroptera, more than 2,000 species being known, most of 

 them tropical in distribution, fewer than 100 occurring in the 

 United States. For the most part our species are beneficial, 

 the majority of them living on the foliage of herbs and shrubs, 

 where they lie concealed and wait for their prey, in the form 

 of small plant-feeding insects, to come within striking distance. 

 A few of the larger forms, when picked up incautiously, often 

 insert their beak quickly and deeply into a finger, causing a 

 deep puncture acompanied by a sharp stinging sensation not 

 unlike that produced by a hornet. This results in numbness 

 and soreness which sometimes lasts for several days. The 

 North American species are distributed among nine subfam- 

 ilies, all of which are represented in our territory. The prin- 

 cipal literature pertaining to them is by Stal, 1872, 1874 ; 

 Uhler, 1884; Champion, 1898; Caudell, 1901; Fracker, 1913; 

 Neiva, 1914; Del Ponte, 1920; Bueno, 1923. 



KEY TO NORTH AMERICAN SUBFAMILIES OF REDUVIILVE. 66 



a. Ocelli absent; elytra always present and entire; length less than 

 9 mm. 



b. Anteocular part of head subcylindrical, twice as long as inter- 



ocular width; tarsi 1-jointed. Subfamily I. Carthasin^e, p. 538. 

 bb. Anteocular part of head obtusely triangular, not longer than inter- 

 ocular width; tarsi 3-jointed. Subfamily II. Saicin^e, p. 539. 

 aa. Ocelli present; elytra sometimes very short; length, 10 or more mm. 



c. Elytra without a quadrangular or discoidal cell at outer basal angle 



of the membrane; front, and usually the middle, tibiae ending in 

 an oval or oblong lobe or plate which is concave and more or less 

 spongy beneath. 

 d. Ocelli placed behind an imaginary transverse line connecting the 

 hind margin of the eyes; second joint of antenna? simple. 

 e. Apex of scutellum narrow, without spines, or prolonged backward 

 as a single spine; antennae 4-jointed. 

 /. Thorax constricted at or in front of middle; front coxae terete, 

 their outer side convex. Subfamily IV. Reduviin>e, p. 552. 

 //. Thorax constricted behind the middle; front coxae with outer 

 side fiat or concave. Subfamily V. Pirating, p. 556. 



ee. Apex of scutellum broad, emarginate, armed with two spines; 

 antennae apparently 8-jointed. 



Subfamily VI. Ectrichodiin^e, p. 561. 



'•'■The sequence of the subfamilies in this key is not the same as followed in 

 the text, the Stenopodinre there being placed next to the Saieina?, to which they are 

 most closely allied. 



