Aulocara femoratum

Distinguished from the congeneric bigheaded grasshopper (Aulocara elliotti) by: (1) the posterior margin of the eighth abdominal sternum in females has two deep clefts (absent in A. elliotti); (2) slightly smaller body size; (3) nymphs are lighter colored with greater contrast between background tan/cream and fuscous markings versus the drab gray of A. elliotti nymphs. The X-figure on the pronotum is present in both species. The whitecrossed grasshopper has three dark bands on the hind femur versus two in A. elliotti.

Primarily inhabits mixedgrass prairie where western wheatgrass and needle-and-thread are abundant alongside the short grass blue grama. Also occurs in bunchgrass prairie, shortgrass prairie, and desert prairies. Within mixedgrass prairie, prefers more luxuriant vegetation types with greater abundance of mid grasses. Occupies sites with small bare areas (1–6 square inches) interspersed among grassy vegetation for resting and oviposition.

Western North America from southern Canada to central Mexico. Recorded from Colorado, Kansas, Nebraska, Oklahoma, Wyoming, Montana, Arizona, New Mexico, and Texas. Distribution covers approximately 60 percent of that of Aulocara elliotti. More prevalent in Montana than in Wyoming based on survey data.

Intermediate-hatching species. Eggs begin hatching in the first week of June in the mixedgrass prairie of Montana and Wyoming, approximately 10–14 days after Aulocara elliotti. Nymphs emerge over a two-week period. Adults appear during the first and second weeks of July. Males fledge before females. Mating begins approximately three weeks after female fledging. One generation annually with overwintering in the egg stage.

General grass feeder exploiting perennial grasses and sedges. In mixedgrass prairie of eastern Wyoming, greatest utilization of western wheatgrass and needleleaf sedge. In desert prairie of southwest Texas, main host plants are buffalograss and blue grama. Also consumes burrograss, fall witchgrass, sideoats grama, hairy grama, and Sporobolus species. Males ingest more short grasses and sedge; females ingest more mid grasses due to behavioral differences—males walk extensively on the ground while females are more sedentary and climb mid grasses to feed. Has been observed feeding on dry fallen grass and dry cow dung. Accepts bran bait.

• Pascopyrum smithii - primary hostwestern wheatgrass; major component of diet in mixedgrass prairie
• Hesperostipa comata - primary hostneedle-and-thread; major component of diet
• Bouteloua gracilis - primary hostblue grama; dominant short grass in preferred habitat
• Carex duriuscula - primary hostneedleleaf sedge; heavily utilized
• Bouteloua dactyloides - primary hostbuffalograss; main host in desert prairie
• Scleropogon brevifolius - secondary hostburrograss
• Digitaria cognata - secondary hostfall witchgrass
• Bouteloua curtipendula - secondary hostsideoats grama
• Bouteloua hirsuta - secondary hosthairy grama

Egg stage overwinters. Eggs laid in pods 9/16 to 10/16 inch long and 1/4 inch in diameter, inserted vertically 1/8 inch below ground surface to 3/4 inch depth. Pods have unusually strong, thick walls and lack a nipple on the cap (distinguishing them from A. elliotti pods). Egg mass contains 9–11 pale yellow eggs, 4.7–5.2 mm long. Nymphs emerge in mid-spring; males develop through four instars in minimum 30 days, females through five instars in minimum 42 days. Adults appear in early July, mate three weeks after female fledging, and oviposit in summer. One generation annually.

Geophilous insect spending most of day and all night on the ground. Rests on bare areas of 1–10 square inches interspersed among vegetation, not under canopy. Basks in morning by turning side perpendicular to sun rays and lowering associated hindleg to expose abdomen. Morning activity period lasts about two hours. When temperatures rise, employs thermoregulatory behaviors: stilting (raising body on legs), crawling onto short vegetation to rest diagonally facing sun, climbing mid grass stems 2–7 inches, or seeking shade. Males walk extensively on ground to find and court females; females more sedentary. Courtship involves hindleg movements resembling stridulation. Flushed flight covers 2–6 feet at 4–10 inch heights, silent and straight, landing facing away from intruder.

Primary consumer in grassland ecosystems. Functions as a generalist herbivore on perennial grasses and sedges. Occasionally becomes locally dominant in grasshopper assemblages, reaching densities up to 13 adults per square yard, though usually subdominant to Aulocara elliotti or other species. Serves as prey for various vertebrate and invertebrate predators. Less injurious to vegetation than A. elliotti due to smaller size, lower densities, and thriftier feeding habits with little leaf clipping.

Occasional pest of rangeland forage grasses. Reaches densities high enough to cause economic damage in certain mixedgrass prairie habitats, though usually subdominant in outbreak assemblages where A. elliotti is dominant. Less damaging than A. elliotti due to smaller size, lower densities, less frequent occurrence, and minimal leaf clipping. Subject to control efforts when part of damaging grasshopper assemblages. Consumes bran bait, making it susceptible to bait-based control methods.

• Aulocara elliottiCongeneric species with similar X-marked pronotum and general appearance. Distinguished by larger size, two dark bands on hind femur versus three, absence of deep clefts on female eighth abdominal sternum, earlier hatching, and drab gray nymph coloration versus light tan with high contrast.
• Boopedon nubilumOccurs in similar western grassland habitats and may be found in same assemblages. Distinguished by striking sexual dimorphism (black males, pale brown females), larger size, and different pronotal markings.

• grasshopper
• slant-faced grasshopper
• western grasslands
• mixedgrass prairie
• generalist herbivore
• occasional pest
• sexual dimorphism
• thermoregulation

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Bigheaded Grasshopper
• Whitecrossed Grasshopper
• Grasshoppers of Colorado
• Grasshoppers of Colorado
• Ebony Grasshopper
• Grasshoppers of Colorado