Opeia obscura (Thomas)

 
Adult male Adult female

Common name - Obscure grasshopper (Heifer, 1972).

Geographic distribution - Alberta, Saskatchewan and Manitoba (Canada) and western Wisconsin south to Mexico. Also in California and Nevada (Otte, 1981). O. obscura is found primarily in eastern Colorado (Alexander, 1941).

Colorado Distribution Map

Habitat - eroded ground in areas of short grass (Brooks, 1958; McNeill, 1896).

Food habits - graminivorous, preferring buffalo grass, sunsedge, prairie sandreed, threeawn, sixweeks fescue, muhly, saltgrass, Sandberg bluegrass, dropseed, blue grama and western wheatgrass (Ball et al.,1942; Brooks, 1958; Brusven, 1967; Hewitt, 1977; Kumar et al.,1976; Mulkern et al.,1969).

Eggs - 8 whitish eggs are deposited in two columns within the pod. Average egg length, 4.2 mm; average diameter, 1.1 mm (Onsager and Mulkern, 1963).

Nymph - five instars (Ramsey, 1964).

Adult - small to medium size. Face is slanted back. Vertex is rounded. Median carina of head is distinct. Antennae are sword-shaped. Dorsal posterior margin of pronotum is rounded. Coloration is extremely variable. Typically, the back is brown or green and nearly plain. Sometimes a dark streak runs along the median carina of the pronotum. The grasshopper's sides have a stripe that runs backward from the eye widens and becomes more obscure. This stripe is below the lateral carinae and varies in color and intensity. Tegmina of females have an irregular, dark longitudinal stripe or series of spots. Below the dark stripe is a whitish streak. Wings are clear. Male length, 16 mm; female, 25 mm (Ball et al.,1942; McNeill, 1896).
 
Pronotum (Side view) Pronotum (Top view) Antenna

Seasonal history - overwinters in the egg stage. Adults are found in late summer and autumn (Ball et al.,1952; Bhatnager and Pfadt, 1973).

Abundance and importance - sometimes common. Eats high-value forage and is of economic importance to grasslands (Heifer, 1972; Mulkern et al., 1969).

O. obscura fact sheet from the Field Guide to Common Western Grasshoppers
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