Arrhenopeplus brunneus

Adults are distinguished by the combination of slanted face, filiform antennae, vertical ivory facial band, ivory streak from eye onto pronotal lateral carina, long wings with spotted tegmina and ivory streak near front edge, and orange or red hind tibia. The three light spots in the dark dorsal stripe of the hind femur medial area are diagnostic. Nymphs are identified by progressive development of these characters: incised median carina appears in instars III-IV, three light spots in hind femur stripe become distinct in instars III-IV, and hind tibia changes from fuscous (instars I-II) to straw-colored (instars III-IV). The immaculate tan dorsum pattern occurs in both nymphs and adults and may cause confusion with other species. Distinguished from Boopedon nubilum by color pattern and wing length; from Chorthippus curtipennis by facial markings and hind tibia color.

Mixedgrass and bunchgrass prairies, mountain meadows, parklands, and alpine tundra. In the northern mixedgrass prairie, restricted to suitable hillsides with small, local populations. Requires habitats with green grasses and sedges for food, ground litter for shelter, and interspersed bare ground for basking and oviposition.

Northwestern United States; extends into eastern North Dakota and southwestern Manitoba in the northern mixedgrass prairie. Documented from the Laramie Range and Big Horn Mountains of Wyoming, with populations in mountain meadows and foothills. Altitudinal range: 1,600 to 11,100 feet.

Hatching occurs in June, with period lasting approximately two weeks. Adults normally appear in July in northern mixedgrass prairie and mountain meadows; timing varies with seasonal temperatures (e.g., July 14 in 1994 versus August 10 in 1995 in Laramie Range). Oviposition begins approximately 18 days after first adult appearance and continues into late September; extended into early October in years with late fall. Two-year life cycle suspected in mountain meadows and northern grasslands.

Feeds on grasses and sedges. Documented host plants include Idaho fescue, spikefescue, thickspike wheatgrass (Elymus lanceolatus), needleandthread, rock sedge, and threadleaf sedge. In northern mixedgrass prairie, feeds on Agropyron, Bouteloua, Carex, Koeleria, and Stipa. Exhibits selectivity among grass species as confirmed by two-choice cage tests. Feeding behavior involves raising diagonally on host plant, cutting leaf 1/2 inch or more above base, holding cut section with front tarsi, and consuming from cut end to tip while resting horizontally on ground. Also feeds in short bouts on ground litter.

Eggs overwinter in soil pods. Hatching in June; nymphal development through four instars requires 40-46 days. Adults appear July-August. Oviposition occurs late summer to early fall. Evidence suggests two-year life cycle in mountain meadows and northern grasslands, though this requires further research. Embryonic development and diapause not studied.

Geophilous (ground-dwelling) species. Spends day on ground surface, night hidden in ground litter 1/2 inch deep. Basks for approximately three hours after appearing on ground surface two hours post-sunrise, presenting side perpendicular to sun with associated hindleg lowered to expose abdomen. Second basking period occurs in afternoon. Seeks shelter shortly before sunset. Flushed flight is straight and silent, traveling 2-8 feet at heights of 4-6 inches, usually landing on ground headed away from intruder. Feeds by climbing host plant, cutting leaf, and consuming while resting on ground. Cuts leaves 1/2 to 2 inches above base; may turn head-down on plant to cut additional leaves.

Grass-feeding species; contributes to grassland herbivory and nutrient cycling. During irruptions, becomes dominant member of grasshopper assemblages, comprising up to 50% of local populations. Serves as prey for various vertebrate and invertebrate predators. Eggs and nymphs subject to predation by birds, rodents, and insects.

Economic pest of mountain and foothill grasslands during population irruptions. In 1920 outbreak in southwestern British Columbia, dense infestation covering 2,000 square miles caused considerable damage to range grasses; species comprised 50% of assemblage. From 1988-1994 in Wyoming mountains and foothills, densities ranged from less than 0.1 to 15 per square yard; 80% of surveyed sites contained less than one individual per square yard. As subdominant species, may add to damage caused by dominant species. No experimental damage studies conducted; estimates based on adult weights. Managed through integrated pest management approaches for grasshopper control.

• Boopedon nubilumBoth in Gomphocerinae with slanted faces; distinguished by B. brunneus having longer wings, distinct facial ivory band, and orange/red hind tibia versus B. nubilum's different coloration and wing proportions
• Chorthippus curtipennisBoth slantfaced grasshoppers in similar habitats; distinguished by B. brunneus having ivory facial band, three light spots in hind femur stripe, and orange/red hind tibia versus C. curtipennis's different facial markings and hind leg coloration
• Camnula pellucidaOften co-occurs in assemblages; C. pellucida is bandwinged (Oedipodinae) with different wing structure, color pattern, and behavior; B. brunneus lacks the colored hindwings characteristic of Oedipodinae

• grasshopper
• Acrididae
• Gomphocerinae
• pest
• range pest
• mountain meadow
• mixedgrass prairie
• grass feeder
• geophilous
• two-year life cycle
• western North America
• Wyoming
• Montana
• Colorado
• British Columbia
• Manitoba
• North Dakota

• BugGuide
• Grasshoppers of Colorado
• Grasshoppers of Colorado
• Grasshoppers of Colorado
• Species Records and Accounts
• Bruner Slantfaced Grasshopper
• Field Guide