Common name - Tiny spur-throated grasshopper (Heifer, 1972).
Geographic distribution - extends eastward across the Great Plains, ranging from Manitoba (Canada) and Minnesota to Montana and British Columbia (Canada); south to Colorado and Nebraska (Hebard, 1928; Hebard, 1929; Helfer, 1972). Found primarily in central Colorado extending onto the plains along the front range.
Habitat - commonly found in open, grassy areas and sandy or gravelly soils. Present from the plains to the foothills and mountains up to 8,000 ft. (Alexander, 1941; Criddle, 1933a; Hebard, 1928; Hebard, 1929; Helfer, 1972; Somes, 1914).
Food habits - graminivorous in its feeding habits, but it occasionally feeds on forbes. Major food plants include blue grama, needleandthread, western wheatgrass and threadleaf sedge (Criddle, 1933a; Helfer, 1972; Mulkern et al., 1969).
Eggs - average egg length, 3.9 mm; average diameter, 1.1 mm. Egg pods contain up to 10 pale tan eggs arranged in two columns (Onsager and Mulkern, 1963).
Nymph - five instars.
Adult - small size. Brownish to light grey in color. Head is brownish and flecked with dark black spots. Behind the eye is a broad black band often edged on top with yellow that extends across the upper half of the lateral lobes of the prozona. Dorsal posterior margin of pronotum is rounded. Tegmina usually are longer than abdomen and reaching the tip of the hind femora, with yellowish and blackish-brown dots scattered throughout. Wings are colorless. Hind femora are straw yellow on lower face with a pair of conspicuous oblique pale bars. Hind tibiae are pale blue. Cerci are thick and swollen at base, narrowing at middle and broadening again and then forking. Furculae are very small and triangular. Subgenital plate is narrow and abruptly elevated at the exteme apical margin. Apical margin is notched in the middle. Male length,15.5 mm; female, 20 mm (Helfer, 1972; Scudder, 1897; Somes, 1914).
Seasonal history - in northern Colorado, nymphs are present from June through August; adults are found from August through October.
Abundance and importance - not abundant enough to be considered an injurious species in Colorado (Gillette, 1904).
M. infantilis fact sheet from the Field Guide to Common Western Grasshoppers
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