14 IOWA STUDIES IN NATURAL HISTORY 
Key to the famlies of Pentatomiformes 
Connexivum of abdomen with six visible dorsal segments; first 
ventral abdominal segment entirely or almost entirely con- 
cealed by the metasternum, visible only at middle. Tibiae set 
with rows. of heavy (spies...) cee ee CYDNIDAE (2) 
Connexivum of abdomen with seven visible dorsal segments; 
second (apparently the first) ventral abdominal segment vis- 
ible for its entire width. Tuibiae not strongly spinose but often 
thickly haired. 
Scutellum covering almost entire abdomen and usually convex; 
colors;dulle 2 eee. eee ee ee SCUTELLERIDAE (1) 
Seutellum usually moderate in size, more or less narrowed at 
apex. If scutellum is large, colors are bright and econtrasty or 
the pronotum bears a prominent tooth anterior to the lateral 
BMP OS yes ecco eee PENTATOMIDAE (38) 
Family SCUTELLERIDAE (Leach) 
This family is more characteristic of the Palaearctic, Ethi- 
opian, Oriental and Australian regions; less than one-half the 
total number of described species are from Nearctie and Neo- 
tropical regions. 
The species of the family exhibit great variation in color and 
size, on this account giving considerable difficulty in their deter- 
mination which has resulted, in some cases, in extended syn- 
onymy. 
Four species placed in two genera are recorded for Iowa. In 
the United States the members of the family are more abundant 
to the west and southwest. The principal diagnostic characters 
may be briefly summarized as follows: 
Scutellum entirely or almost entirely covering the abdomen. Veins of 
membrane arising from a vein at exterior basal angle running transversely, 
arcuately inwards, gradually retreating from the interior basal angle; 
corium broad, obtuse at apex. Primary and subtended veins of wing 
remote, enclosing a rather wide area, not regularly converging towards 
apex; hamus present. Frenum absent. Basal ventral abdominal segment 
distinct at the sides; connexivum of abdomen with seven dorsal segments ; 
six segments only are distinct from below. Tibiae not strongly spinose. 
Key to the subfamilies 
Venter with elongate, finely and densely striate stridulating 
