Montana Field Guide

The following is taken from Brooks (1958), Helfer (1971), Otte (1984), Vickery and Kevan (1985), McDaniel (1987), Brust et al. (2008), and Scott (2010). This medium-sized species is sandy colored to grayish brown with scattered dark spots. The median carina (ridge) of the pronotum is obvious, but low, and cut by 2 sulci (grooves). The lateral lobe is extended to a rounded tooth at the ventral-posterior edge (see illustration). The tegmina (forewings) bear no bands and closely match sandy ground. The hindwing disk is yellow with a prominent black band, short spur, and wide transparent tip. The outerface of the hind femur is speckled with dark spots with some coalescing into larger spots. The inner face of the hind femur is reddish with the basal third being black and apical third bearing a black band. The hind tibia is red, sometimes merging into a pale area at the base.

Communicative behavior/Crepitation*
Flight is short and low to the ground. Both genders crepitate just before landing. Courting males stridulate* with 4 strokes when about 9 inches from the female and then mount for copulation. Femur-tipping sometimes proceeds before stridulation. Femur-tipping, femur shaking, and striking the ground with the hind tibia is used in male-to-male aggressive displays (Otte 1970, and Vickery and Kevan 1985).

*Crepitation is the sound produced by grasshoppers making a clicking or snapping noise with their wings when in flight, during courtship, territorial encounters or being disturbed.

*Stridulation is rubbing one body part against another, usually the hind femur against the forewing in the case of the Band-winged Grasshoppers. This is often used for attracting a female during courtship (Otte 1970).

Note: The Trimerotropis is the largest genus within the bandwing group. Ten species occur in Montana and possess considerable morphological characteristics and variations in color and markings among individuals of the same species. It is not an easy genus to identify to the species level. In addition, this genus is easily confused with other grasshopper genera (refer to “Similar species” below). However, there are certain morphological characters which can help in determining a Trimerotropis: (A) The body is elongate and slender. (B) The pronotal (thorax) carinal crest is prominent, but low, and always cut by 2 sulci (grooves) before the middle. (C) The tegmina (forewings) extend beyond the abdominal tip. (D) The disk of the hindwings is always yellow, yellow-green, or blue, never red or orange. (E) The eyes are relatively large, but not bulbus (Otte 1984, Vickery and Kevan 1985).

The Toothed Field Grasshopper overwinters in the egg stage. Nymphs appear in early June and adults occur from July to August, sometimes into September (Otte 1984, Vickery and Kevan 1985, Brust et al. 2008, and Scott 2010).

The following comes from Brooks (1958), Helfer (1971), Otte (1984), Vickery and Kevan (1985), McDaniel (1987), Brust et al. (2008), and Scott (2010). The body length to end of forewings for males is 24-43 mm, and for females 31-43 mm. The lower posterior angle of pronotum lateral lobe is extended to a rounded point, thus, its common name (see illustration).

This species is easily confused with other Trimerotropis species, and other Montana species in the genera such as Spharagemon, Derotmema, Circotettix, and Mestobregma (Scott 2010 and field notes).

Inhabits sandy habitats with sparse vegetation, such as dunes, hillsides, and blowouts (Otte 1984, and Vickery and Kevan 1985).

Not well known but has been noted to feed on Pediomelum sp. (formally Psoralea sp.), and a mixture of grasses, forbs, and dead or dying insects (Brust et al. 2008).

No studies have currently been found in the literature.