SUBFAMILY I. — PENTATOMIN^E. 121 



and Lo.va) longer than the tylus and more rarely (Proxys) dis- 

 tinctly shorter. The humeral angles often end in a strong 

 spine and the side margins of pronotum in two genera (Eu- 

 schistus and Lo.va) are distinctly crenulate. The subtribe com- 

 prises some of our most common Pentatomids (Mormidea, Eu- 

 schistus and Cosmopepla) , three genera to which the name "stink- 

 bug" pre-eminently belongs. Eleven of the 25 eastern genera 

 comprising the tribe Pentatomini belong in this group, and an- 

 other is included in the key, as its single species probably oc- 

 curs in western Illinois. 



KEY TO EASTERN GENERA OF SUBTRIBE II OF PENTATOMINI. 



a. Cheeks with side margins not thickened and reflexed; head (except 

 in Neottiglossa) not strongly deflexed; color (except in Cosmo- 

 pepla) not black or blue, variegated with red or yellow. 

 6. Smaller, length not over 15 mm. ; cheeks with tips obtuse, rarely 

 longer than tylus and then converging and contiguous in front 

 of it; side margins of pronotum (except in Euschistus) not crenu- 

 late. 



c. Humeral angles of pronotum without an obtuse projecting process 

 with emargination behind. 

 d. Scutellum shorter than corium, its apical third narrower than 

 apex of corium with tip not broadly rounded. 

 e. Hind tibiae not sulcate or grooved above throughout their length. 

 /. First joint of beak distinctly longer than bucculae; humeral 

 angles of pronotum (in our species) not spined; scutellum 

 either with white margins or a large white spot on each basal 

 angle. VI. Mormidea, p. 122. 



ff. First joint of beak not longer than bucculae; humeral angles 

 of pronotum with long spines; scutellum without white mar- 

 gins or large white spots at base. 

 g. Tylus rounded at apex, not surpassing cheeks; eyes and pro- 

 notum contiguous; humeral spines directed strongly for- 

 ward. VII. Solubea, p. 126. 

 gg. Tylus acute at apex, strongly surpassing cheeks; eyes well 

 advanced in front of pronotum; humeral spines directed 

 outward. VIII. Proxys, p. 127. 

 ee. Hind tibiae sulcate above throughout their length. 



h. Side margins of pronotum crenulate; humeral angles promi- 

 nent, usually acute or acuminate. IX. Euschistus, p. 129. 

 hh. Side margins of pronotum not crenulate; humeral angles ob- 

 tusely rounded. 

 i. Margins of front half of pronotum not strongly flattened ; 

 beak not passing hind coxae; frena reaching middle of scu- 

 tellum; length less than 10 mm. X. Hymenarcys, p. 142. 



