Montana Field Guide

The following is taken from Hebard (1928), Brooks (1958), Helfer (1971), Otte (1981), Capinera and Sechrist (1982), Vickery and Kevan (1985), McDaniel (1987), Pfadt (2002), Capinera et al. (2004), and Scott (2010). Adults possess club-shaped (clavate) antennae which are grayish-white to brown. Body color is gray, brown, or green. Each abdominal segment bears a dark patch. A vertical white stripe occurs on the lateral head side in front of the eye and the frons. Male wings (tegmina) extend to or beyond the abdominal tip, female wings are shorter, about half the length of the abdomen. Hind tibia is yellow to brown.

Eggs begin to hatch from mid-May to early June. Adults become common from mid-July through September (Otte 1981, Capinera and Sechrist 1982, Vickery and Kevan 1985, McDaniel 1987, Pfadt 2002, Capinera et al. 2004, and Scott 2010).

The following comes from Hebard (1928), Brooks (1958), Helfer (1971), Otte (1981), Capinera and Sechrist (1982), Vickery and Kevan (1985), McDaniel (1987), Pfadt (2002), Capinera et al. (2004), and Scott (2010). The males’ body length is 16 to 20 mm and females is 18 to 25 mm. Three, median and lateral, definite dorsal ridges (carina) cut by a single sulcus occur on the pronotum (thorax) and are constricted inward at the middle. Male wings (tegmina) extend to or beyond the abdominal tip, female wings are shorter, about half the length of the abdomen.

Could be confused with the Shasta Slant-faced Grasshopper (Bruneria shastana), but the club-shaped antennae of A. clavatus is diagnostic and easily confirms its identification from B. shastana.

Favors dry, sandy, grassy fields and pastures. At higher elevations it is found in alpine meadows and tundra. In some areas it is considered an alpine and boreal species (Capinera and Sechrist 1982, Capinera et al. 2004, McDaniel 1987, Otte 1981, Pfadt 2002, and Vickery and Kevan 1985).

Primarily feeds on a diversity of grasses and sedges in mixed grass-bunchgrass prairies and mountain meadows. At higher altitudes it also feeds on forbs, especially thistle (Cirsium spp.) (Capinera and Sechrist 1982, Otte 1981, Pfadt 2002, Capinera et al. 2004, and Vickery and Kevan 1985).

The following is taken from Capinera and Sechrist (1982), Otte (1981), Pfadt (2002), Capinera et al. (2004), and Vickery and Kevan (1985). The Club-horned Grasshopper has an egg hatching period of 3 to 4 weeks. Nymphs pass through 4 instars which develop rapidly to the adult stage. Adult stages are reached in about 30 days on the plains and 42 days in alpine habitats after hatching. Females oviposit eggs amid the roots of grasses and sedges. Egg pods contain 3 to 8 eggs arranged in two rows. Studies indicate that eggs laid by populations in high altitudes pass through two winters before hatching, whereas those from lower elevations hatch after one winter.