Encoptolophus sordidus (Burmeister)


Adult female

Common name - Dusky grasshopper (Bailey and Riegert, 1971).

Geographic distribution - from Alberta (Canada), Montana and Colorado to Manitoba (Canada), the Dakotas, Nebraska, Kansas, Oklahoma and Texas (Brooks, 1958). In Colorado it generally is found from the eastern plains to the mountain foothills (Hebard, 1929).

Colorado Distribution Map

Habitat - found mainly on heavily grazed areas of homogeneous grass (Mulkern et al., 1964).

Food habits - food habits are influenced by what is available. E. sordidus is primarly a grass feeder but will eat forbs when starved. This ability to change food habits perhaps explains its widespread distribution in North America. Its preferred foods are western wheatgrass, thickspike wheatgrass and needleleaf sedge in Canada. In Kansas it prefers bluegrass, sideoats grama, Sandberg bluegrass and carex. It also prefers blue grama. Cannibalism has been observed during food or water shortages (Bailey and Riegert, 1971; Hewitt, 1977; Mulkern et al., 1969).

Eggs - each pod contains 16 tan-colored eggs in two columns. Average egg length, 4.1 mm; average diameter, 1 mm (Onsager and Mulkern, 1963).

Nymph - five instars (Ramsay, 1964).

Adult - medium size. General color is brownish. Face is vertical, and vertex is rounded. Antennae expand slightly toward the tip, Median carina of pronotum is well developed with a notch near the middle. Dorsal posterior margin of pronotum is a rounded right angle. Tegmina have three dark bands. Wings are nearly transparent but smoky near the edge. Hind tibiae are brown to lavender. Male length, 22 mm; female, 30 mm (Ball et al., 1942; Brooks, 1958).
It dwells on the soil surface, feeding and roosting close to the ground. Flight is accompanied by sharp, rapid clicking (Bailey and Riegert, 1972).
 
Tegmen Pronotum (Side view)

Oviposition - females prefer calcareous soil for egg laying (isely, 1938).

Seasonal history - eggs overwinter and hatch in late June to late July. Adults appear in late August (Carothers, 1924; Mulkern et al., 1964; Newton et al., 1954).

Abundance and importance - common in late summer and fall. It feeds mostly on range grasses but is also important at times in cultivated areas, especially alfalfa fields (Alexander, 1941; Ball et al., 1942).

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