16 THE ACRIDIIDAE OF MINNESOTA 
SUBFAMILY TRYXALINAE 
The subfamily Tryxalinae is exceedingly closely related to the 
Oedipodinae and the differentiation of these two 1s sometimes an ex- 
tremely difficult matter. While it is true that in general the forms are 
readily placed, yet on the other hand there are forms in which the 
characteristics of the two subfamilies are so mtermingled that separa- 
tion becomes a matter of arbitrary rule. The characteristic forms of 
Tryxalinae have an oblique front with the vertex horizontal or even 
slightly ascending, but in the Oedipodinae also forms are found having 
similar characters. ‘There are a few characters which may be relied 
upon to differentiate these subfamilies, at least so far as our species 
are concerned. In the Try.valinae the carina of the pronotum is never 
crested, or cut by more than one sulcus save in Mecostethus, while in 
the Oedipodinae the carina may be cut by one, two, or no sulci 
and is often crested. In the Tryxalinae we have no forms with colored 
wings, while in the Oedipodinae practically all of our species have at 
least the basal part of the wings distinctly colored. 
The insects of the Tryxalinae have in general slender bodies, often 
with elongate, cone-shaped heads much suggesting the Conocephalinae 
among the Locustids. Long- and short-winged forms of species are 
common and the coloration is also extremely variable, there being 
often distinctly green and brown forms with all the intermediate tints. 
The subfamily in general frequents tall grasses, and such plant forma- 
tions as the Carices offer the most common habitat, although some 
species are more commonly found amid the scattered vegetation of 
sandy areas. Usually the postericr legs, while long, are very slender 
and the insects in general have much poorer leaping powers than 
those of related groups, all appearing to depend more upon flight as 
a means of escape from danger. The coloration is such, in many 
forms, as to render the insects almost invisible when feeding and these 
species appear in large measure to rely upon this protective colora- 
tion. While, as has been suggested, flight is the common means of 
escape, in many forms the wing area is too small to aid greatly in 
this and even in those forms with well-developed wings the flight is 
rather feeble and in most cases not well sustained. 
More than thirty genera belonging to this subfamily are known 
in North America and of these less than a dozen are represented in 
Minnesota. Several of our species are extremely rare and we have 
but one species, Stenobothrus curtipennis, which becomes abundant 
enough to be of economic importance. ‘The following key will serve 
to distinguish the genera of this subfamily as represented in our State: 
