Montana Field Guide

The following comes from Hebard (1928), Helfer (1971), Vickery and Kevan (1985), Pfadt (2002), Capinera and Sechrist (1982), Capinera et al. (2004), Brust et al. (2008), and Scott (2010). The head is exceptionally large compared to the thorax, being broad, deep, and noticeably slanted in lateral view. Wings (tegmina) usually short, extending only to the second or third abdominal segment. There are rarer individuals (about 5 percent in a population) with long wings extending a few millimeters beyond the abdominal tip. Hind tibia is blue, greenish, or purplish. The general body color is light gray or brownish dorsally and often yellowish ventrally.

Overwinters in the egg stage. Nymphs appear in late May and June. Adults are found from early July through October, sometimes into November (Vickery and Kevan 1985, Pfadt 2002, Capinera and Sechrist 1982, Capinera et al. 2004, Brust et al.2008, and Scott 2010).

The following comes from Hebard (1928), Helfer (1971), Vickery and Kevan (1985), Pfadt (2002), Capinera and Sechrist (1982), Capinera et al. (2004), Brust et al. (2008), and Scott (2010). The male body length is 21 to 25 mm, and female 23 to 33 mm. The dorsal pronotum (thorax) constricted posteriorly. Dorsal stripe on the outer face of the hind femur is brown, extending slightly into the medial area and yellowish below.

Could be confused for a Slant-faced Grasshopper, family Gomphocerinae, which lacks the ventral tubercle between the front legs or for any of the short-winged Melanoplus species. Check male genitalia for comparisons.

This species prefers lush, tallgrass prairies and mixed tall grasslands, often being the dominant species present in such habitats. In shorter types of grasslands, it may be locally abundant in tall grass patches in swales, ravines, coulees, along streams, and roadsides (Pfadt 2002, Capinera and Sechrist 1982, and Capinera et al. 2004).

The Large-headed Grasshopper feeds almost exclusively on a diversity of grass species, which is unusual for a spur-throated grasshopper. Feeds heavily on little bluestem, (Schizachyrium scoparium), big bluestem, (Andropogon gerardii), and Kentucky bluegrass, (Poa pratensis) in tallgrass prairies. In mixed grass areas, it favors western wheatgrass, (Elymus smithii). Also favors some forbs, such as dandelion, salsify and skeletonweed (Stephanomeria) (Pfadt 2002, Capinera and Sechrist 1982, and Capinera et al. 2004).

The following comes from Pfadt (2002), Capinera and Sechrist (1982), and Capinera et al. (2004). Nymphs pass through 5 instars and develop slowly. Development time from instar I to adult stage requires about 55 days. In laboratory studies, short-winged females produced 120 eggs during a reproductive period set at 25 days. Pods of short-winged forms usually contain 28 eggs, whereas pods of long-winged forms contain 20 to 24 eggs arranged in two columns. Data relative to egg laying sites are uncertain, but some have been observed to occur in the crowns of grass clumps.

Short-winged forms generally remain in the same area in which they developed. However, if the site dries and lacks food, they have been observed to move to more lush areas up to 100 feet. The less common long-winged forms possess strong powers of flight and can disperse considerable distances, which probably accounts for the species' large geographical distribution. In tallgrass prairies, the Big-headed Grasshopper is of little pest importance. In mixed-grass prairies, especially during droughts, it can have significant impacts of rangeland forage. In fall, adults may invade fields of winter wheat, feed on the seedlings, and consume the entire plants to ground level (Pfadt 2002).