82 IOWA STUDIES IN NATURAL HISTORY 
We have taken specimens oftenest by sweeping in fields of red 
clover and timothy, particularly in low places. Maize and wheat 
are recorded as additional food plants. The bug is also said to 
feed on the larvae of the cotton moth, Aletza sp. 
Euschistus tristigmus (Say) (PuatTse VI, Ficure 7) 
1831. Pentatoma tristigma Say, Descr. Het. Hem., 4. 
1837. Pentatoma inconspecta Westwood, Cat. Hope, I, 42. 
1851. EHuschistus luridus Dallas, List Hem., I, 207, Pl. VII, fig. 6. 
1859. Pentatoma tristigma Say, Compl. Writ., I, 314. 
1872. LFEuschistus tristigmus Stal, Svensk. Vet. Handl., 10, no. 4, 26. 
1876. Euschistus tristiymus Uhler, Bull. U. S. Geol. Geogr. Surv., II, 286. 
1880. EHuschistus tristigmus Distant, B. C. A. Rhynch. Het., I, 58. 
1904. EHuschistus tristigmus Van Duzee, Trans. Am. Ent. Soc., XXX, 47. 
1909. EHuschistus tristigmus Kirkaldy, Cat. Hem. (Heterop.), I, 66. 
Ovate, grayish or brownish, rather closely and finely punctured with 
black; a few small, irregular calloused areas. Head densely, rather regu- 
larly punctate, the juga not longer than the tylus, the margins of head be- 
fore eyes only slightly sinuate; a black line from eyes to base of anten- 
nae. Antennae rufous, the apex of fourth segment and the fifth, except 
at base, blackish. Rostrum extending behind posterior coxae, pale yellow- 
ish, the tip black. Pronotum densely punctate with black along anterior 
and antero-lateral margins, the edges of the latter pale, denticulated and 
concavely arcuated; humeri prominent, rounded. Scutellum rather densely, 
finely punctate, the base with three more or less distinct calloused spots, the 
tip whitish. Hemelytra narrower than abdomen, the corium more closely 
and deeply punctate than the embolium and finely aciculate, with a few 
ealloused impunctate areas; embolium rather closely and finely punctured 
to costal edge; membrane brownish with a number of more or less distinct 
brown spots; a dusky spot on each hemelytron and one near the middle of 
the scutellum. Tergum black, the margins of the abdomen black, the edges 
yellowish or reddish and a large spot of the same color at the middle of 
each segment. Venter yellowish or reddish yellow, finely punctured with 
reddish and finely aciculate; a black spot at each incisure; a series of 
black spots on the middle of each of the four last segments, the posterior 
spot largest and more or less oval in outline; in some specimens two or 
three of these spots are wanting but the black spot on the apical segment 
is always present; the smallest spot is nearest the base and the others 
grade larger posteriorly. Ventral thoracic plates coarsely punctured with 
red. Legs yellowish with numerous black dots, the tibiae and under sides 
of femora furnished with sharp black spines; tarsal segments and claws 
fuscous at apices. Length, 10.0-12.0 mm. Width across humeri, 6.5-7.5 
mm. 
In some individuals the black spots on the middle of the ven- 
ter are fused to form a line, while in other specimens the single 
spot on the last segment is much reduced and very faint. The 
tendency to fusion of these spots seems to be more prevalent 
