CYDNIDAE OF THE WESTERN HEMISPHERE — FROESCHNER 629 



Thoracic pleurae (fig. 113): Posterior margins of all segments 

 well-developed; propleuron with posterior convexity low; meso- 

 pleuron with posterior margin touching or overlapping metapleuron 

 for most of width; metapleuron covering posterior coxa, posterior 

 margin expanded as a free, triangular lamella which laterally covers 

 sides of sternites I-III. 



Legs: Male with secondary sexual characters in form of strongly 

 modified spines and angulations on femora and/or tibiae; female 

 without secondary sexual modifications of legs; tarsus present on all 

 legs, II subequal in thickness to I and III. 



Sternites (fig. 173): Sutures entire, not emarginate laterally; III 

 and IV without trichobothria, V to VII each with a single tricho- 

 bothrium located posterior to the spiracle. 



Terminalia: Male genital capsule opening posteriorly (fig. 179); 

 female plates small, anus completely surrounded by an undivided 

 triangular plate (fig. 185). 



Type of subfamily. — Genus Amnestus Dallas (1851, p. 126). 



Distribution.' — From the northern United States south to central 

 Argentina. 



Discussion. — The presence of a distinct claval commissure is a very 

 unusual feature in the Pentatomoidea. Usually the scutellum is 

 enlarged so as to surpass the apices of the clavi and prevent their 

 coming together. This condition plus the trichobothrial arrangement, 

 strongly lamellated posterior margin of the metapleuron, and the 

 unusual secondary sexual modifications of the legs of the males set this 

 genus apart from all the other Cydnidae studied and support the 

 elevation of Hart's tribe Amnestini to full subfamily position. 



Biologically the Amnestinae are known only from fragmentary 

 notes that have appeared in scattered publications. A generalized 

 life cycle deduced from these notes, data on specimens and personal 

 observations may be outlined here: adults hibernate and so probably 

 lay eggs on again becoming active in spring; both nymphs and adults 

 are root-feeders, with the preferred habitat apparently under moist 

 conditions. This latter is surmised from the fact that the adults, 

 which come freely to lights, are collected most abundantly at lights 

 along bodies of water (i.e., bridge and dock lights, streamside cottages, 

 etc.). This preference for a moist habitat is confirmed by such pub- 

 lished statements as "on weeds in slough" (Crevecoeur, 1905) and 

 "on low vegetation along streams" (Blatchley, 1926). The number 

 of generations per year is not indicated by data at hand. 



The subfamily contains the single genus, which is treated here. 



