Montana Field Guide

The following is taken from Vickery and Kevan (1985), Pfadt (2002), Capinera et al. (2004), Capinera and Sechrist (1982), and Scott (2010). This is a large yellow grasshopper with black markings. The outer face of the hind femur has contrasting chevron-like markings which readily distinguishes it from other Melanoplus species. Melanistic (black) forms (morphs) can be encountered in a population which are almost entirely black except for some pale-yellow markings on the top and bottom of the hind femur.

The Differential Grasshopper is a strong flier! Adults are capable of dispersal flights of over 100 miles, and heights have been observed at 1400 feet. Such flight seems to occur in the morning and when temperatures reach 81 degrees F (Pfadt 2002, and Schell et al. 2005).

This species overwinters in the egg stage and begins to hatch in late spring. Adults occur from July to October. Specimens become progressively darker in color as the seasons progress (Vickery and Kevan 1985, and Capinera and Sechrist 1982).

The following is taken from Vickery and Kevan (1985), Pfadt (2002), Capinera and Sechrist (1982), Capinera et al. (2004), and Scott (2010). The body length to end of forewings is 28 to 37 mm for males, 34 to 50 mm for females. The shape of male’s genital cercus is distinctive, which are large and "boot-shaped" and the furcula are small and barely visible. The black chevron markings on the hind femur, of both males and females, are also diagnostic.

Due to its large size and striking color, the Differential Grasshopper can rarely be confused with any other Melanoplus species. There is a subspecies, M .d. nigricans, which is known only from eastern South Dakota, eastward through Minnesota, Wisconsin, Michigan and New Jersey (Vickery and Kevan 1985).

The following comes from Pfadt (2002), Schell et al. (2005). It was originally restricted to areas of tall herbaceous vegetation in wet meadows, swales, and creek bottomlands. With the habitat changes brought about by the advance of human settlement and agricultural development, it spread into weedy vegetation sites of crop borders and roadsides. Across much of its range, large populations can develop over extensive areas of croplands between the Rocky Mountain front and the Mississippi River.

This species is polyphagous, feeding on both grasses and forbs, but usually consumes more forbs than grasses. However, it grows faster, larger, and produces more eggs, when feeding on a mixture. Sunflowers, soybeans, corn, and wheat are readily consumed—but not alfalfa. It also prefers species in the Composite family, Asteracae, such as ragweed, sunflowers, and prickly lettuce (Lactuca serriola) (Pfadt 2002, and Schell et al. 2005).

The following comes from Pfadt (2002) and Schell et al. (2005). After hatching in early spring, the nymphs pass through 6 instars. The fledgling adults often fly into corn, and other crop fields, where they spend several weeks feeding to put on weight and size. During this time, they become sexually mature. Pairs form in the morning and copulation often continue for 20 to 24 hours. Females move to adjacent sod land or rank weeds to oviposit her eggs. She may brace herself against a grass or weed stalk and then work her ovipositor down in the soil. She deposits from 45 to 194 eggs amid the roots and forms a large pod around them. There is one generation per year.

The following is taken from Pfadt (2002) and Schell et al. (2005). The Differential Grasshopper is prone to outbreaks and has a high potential reproductive potential. However, due to it being better adapted to warmer climates, its pest status is more severe in the southern latitudes of its range. This species range, habitat, etc. overlaps that of the Two-striped Grasshopper, (M. bivitattus), another serious pest. Thus, outbreaks of M. differentials occur more frequently farther south while those of M. bivitattus occur farther north. In Montana, M. differentials is seldom likely to reach as severe outbreak levels as M. bivitattus.