Anabrus simplex

Distinguished from other western North American shieldbacked katydids by its ground-dwelling, rangeland habitat and large size. Most other shieldbacked katydids in the region inhabit shrubs and bushes rather than open sagebrush-grass communities. The bifurcated male cercus is diagnostic for species identification; this structure begins developing as a black bump in the fifth instar. The gently upward-curved ovipositor and smooth, shiny cuticle separate it from rougher or more spiny tettigoniids. When compared to grasshoppers (Acrididae), the extremely long antennae and shield-backed body form are distinctive.

Large, robust insect reaching up to 8 cm (3 inches) in length. Adults have a smooth, shiny integument with long antennae characteristic of katydids. Wings are short and non-functional for flight. Sexual dimorphism is pronounced: males average 3,400 mg live weight (960 mg dry weight), females average 4,100 mg live weight (1,330 mg dry weight). Adult males possess diagnostic bifurcated cerci with a distinct shape, with bifurcation becoming evident in the fifth instar as a black bump on the inner surface; female cercus remains small and cone-shaped. The ovipositor curves gently upward. Coloration varies but generally matches the drab tones of sagebrush habitats.

Occupies rangelands dominated by sagebrush (Artemisia spp.) and forbs, particularly in the Great Basin and intermountain mountain ranges. Found in open sagebrush-grass associations where large populations develop. In the Rocky Mountains, occurs from 6,500 feet in forest openings to above 11,000 feet in alpine tundra. Utilizes big sagebrush, other sagebrush species, and saltbush as critical shelter and basking structures. Oviposits in bare ground, often in western harvester ant mounds.

Western North America, ranging from British Columbia and Alberta in Canada south through Washington, Oregon, Idaho, Montana, Wyoming, Nevada, Utah, Colorado, and California in the United States. Distribution has expanded in some areas; notable increase in Saskatchewan, Canada documented in 1938. Populations concentrated in the Great Basin and intermountain west, with outbreak populations historically recorded across 11 western states.

Eggs laid in summer undergo embryonic development through fall, entering diapause for winter dormancy. Hatching begins when soil temperatures reach 40°F, typically in spring, at lower temperatures than most grasshoppers. Nymphal development spans 60-90 days through seven instars. Adults present from mid-summer; in high mountain habitats, two years may be required to complete one generation. Migratory bands most active during daytime when air temperatures range 65-95°F.

Generalist herbivore with documented feeding on over 400 plant species. Preferred forbs include milkvetches (Astragalus), penstemon, arrowleaf balsamroot (Balsamorhiza sagittata), dandelion, and mustards (wild mustard, tumble mustard, pepperweed). Feeds on shrubs including saltbush (Atriplex) and sagebrush species (big sagebrush, budsage, fringed sagebrush). During seed development, climbs plants to feed preferentially on nutritious kernels. Consumes cultivated plants voraciously: wheat, barley, alfalfa, sweetclover, truck crops, and garden vegetables. Will also consume fungi and arthropods. Protein-seeking behavior drives migratory band movement.

Hemimetabolous development with one generation annually (two years in high mountain habitats). Eggs laid singly in bare ground, often in ant mounds; female covers exit hole with soil using ovipositor. Eggs 7-8 mm long, dark brown when laid, turning white then gray during development. Embryonic growth begins at oviposition, completes by fall, diapauses through winter. Seven nymphal instars; molting occurs on vegetation with insect hanging head- or back-downward, completed in 10-20 minutes, followed by consumption of shed exoskeleton. Adults live approximately 20 days after reaching maturity. Female fecundity averages 86 eggs, with maximum recorded 160 eggs; oviposition occurs in bouts at approximately 7-day intervals.

Forms large cohesive migratory bands at high densities, traveling 0.5-1 mile per day and 25-50 miles per season despite flightlessness. Locomotion limited to crawling and hopping. Migration primarily diurnal under clear skies and favorable temperatures (65-95°F). Bands may coalesce or flow through each other when meeting. Exhibits thermoregulatory basking: nymphs emerge after sunrise to bask on east side of shrubs, shifting to west side before sunset. Seeks shelter under shrub canopies, in soil cracks, under clods, or beneath dung during cold, wet, or windy conditions. Sex-role reversed mating system: males produce calling songs, are choosy of mates, and provide large nuptial gifts (spermatophores up to 27% of male body weight) that females consume for egg production. Females compete aggressively for access to males and nutritious gifts.

Significant consumer of primary production in sagebrush ecosystems; at one individual per square yard, consumes forage equivalent to 38 pounds dry weight per acre. Migratory bands redistribute nutrients across landscapes. Serves as prey for diverse predators including California gulls, hawks, crows, rodents, and the digger wasp Palmodes laeviventris. Gut microbiome dominated by Lactobacillaceae, Enterobacteriaceae, and Streptococcaceae contributes to host nutrition, immunity, and potentially social behavior; bacteria likely exchanged with environment. Susceptible to microsporidian pathogen Vairimorpha and entomopathogenic fungi Metarhizium spp.

Major agricultural pest with long history of economic damage in western North America. Outbreaks have persisted 5-21 years; 1931-1948 outbreak peaked at 19 million acres in 11 states. Crop damage in 1937 reached $500,000 in Montana and $383,000 in Wyoming. Damages rangeland forage and destroys cultivated crops in migration paths, particularly sugarbeets, small grains, and alfalfa. Subject to extensive survey and control programs by USDA-APHIS. Indigenous peoples historically harvested as food source; archaeological evidence from Wyoming cave dates to 222 ± 150 years BC. Investigated as potential high-protein poultry feed. Management includes chemical pesticides, poisoned baits (historically), and biological control using Metarhizium fungi.

• Brachystola magnaLubber grasshopper, also large and flightless with periodic outbreaks in western rangelands, but belongs to Romaleidae, has much shorter antennae, and different body proportions.
• Other Decticinae (shieldbacked katydids)Most western shieldbacked katydids inhabit shrubs and bushes rather than ground-dwelling sagebrush communities; differ in size, coloration, and habitat association.
• True crickets (Gryllidae)True crickets have different body form, are generally smaller, and do not form large migratory bands in sagebrush rangelands.

Despite common name 'Mormon cricket,' this species is not a true cricket (family Gryllidae) but a katydid in family Tettigoniidae. The name originated from early Mormon settlers in Utah who experienced devastating outbreaks. Also frequently misidentified as a grasshopper due to its rangeland habitat and pest status, but distinguished by extremely long antennae and shield-backed morphology.

• orthoptera
• tettigoniidae
• katydid
• shieldbacked katydid
• mormon cricket
• pest
• migratory
• sex-role reversal
• sagebrush
• western north america
• outbreak species
• flightless
• nuptial gift
• rangeland
• agricultural pest

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Mormon Cricket
• List of Species Fact Sheets| Grasshoppers of Wyoming and the West
• Grasshoppers of Colorado
• Species Records and Accounts
• Grasshoppers of Colorado
• Wyoming Distribution Atlas
• THE DISTRIBUTION OF THE MORMON CRICKET, ANABRUS SIMPLEX HALDEMAN, IN SASKATCHEWAN
• Structure, culture, and predicted function of the gut microbiome of the Mormon cricket Anabrus simplex (Orthoptera: Tettigoniidae)
• Measuring sexual selection on females in sex‐role‐reversed Mormon crickets (Anabrus simplex, Orthoptera: Tettigoniidae)
• Immediate protein dietary effects on movement and the generalised immunocompetence of migrating Mormon crickets Anabrus simplex (Orthoptera: Tettigoniidae)
• Virulence of the insect-pathogenic fungiMetarhiziumspp. to Mormon crickets,Anabrus simplex(Orthoptera: Tettigoniidae)
• Sexual size and shape dimorphism are consistent with predictions that both natural and sexual selection are driving the evolution of sexual dimorphism in Mormon crickets, Anabrus simplex.