The Mormon cricket (Anabrus simplex) is a large insect native to western North America in rangelands dominated by sagebrush and forbs. Anabrus is a genus in the shield-backed katydid subfamily in the Tettigoniidae family, commonly called katydids, bush crickets, and previously "long-horned grasshoppers". Its common name, "Mormon cricket", is a misnomer: true crickets are of the family Gryllidae.
The Mormon cricket takes its common name from the prominent role it played in the miracle of the gulls, after the Mormon settlers in Utah had encountered them while pushing westward.
Although flightless, the Mormon cricket may travel up to two kilometres a day in its swarming phase, during which it may be a serious agricultural pest and sometimes a traffic hazard.
Mormon crickets can grow to almost 8 cm (3 inches) in length. Individuals vary in coloration: the overall color may be black, brown, red, purple or green. The pronotum, the dorsal "shield" above the prothorax, covers vestigial wings); in some specimens it bears colored markings. The abdomen may have a striped appearance. Like many Tettigoniidae, females have a long ovipositor, which should not be mistaken for a stinger.
As is characteristic of Tettigoniidae, the antennae are long and filamentous. They are in general longer than the head plus body, though the ovipositor extends to beyond the ends of the antennae.
As also is the case in swarming locusts, high population densities of swarming Mormon crickets cause them to undergo changes in morphology and coloration: solitaria, individuals in the solitary phase, typically have green or purple coloration, while swarming individuals, gregaria, are often black, brown or red.
The Mormon cricket shows a marked preference for forbs, but grasses and shrubs such as sagebrush are also consumed. Mormon crickets also eat insects, including other Mormon crickets, especially individuals that have been killed or injured by automobiles or insecticides. Cannibalistic behavior may be a result of protein and salt deficiency. Swarming behavior may in turn be a strategy to avoid predation by other Mormon crickets. A journal documenting an 1846 journey along the Oregon Trail describes an encounter with the crickets and notes their cannibalistic behavior:
Mormon cricket eggs hatch mostly in the spring after they are laid, although in some areas eggs may take as many as five years to hatch. Hatching begins when soil temperatures reach 4 °C (40 °F). The nymphs pass through seven instars before reaching the adult stage, typically taking 60 to 90 days.
Breeding begins within 10 to 14 days of reaching the adult stage. The male passes to the female a large spermatophore which can be up to 27% of his body weight. The spermatophore is mostly food for the female to consume but also contains sperm to fertilize her eggs. This nuptial gift causes swarming-phase females to compete for males, a behavior not seen in solitary-phase females.
The female lays her eggs by thrusting her long ovipositor deep into the soil. Each female can lay over one hundred eggs, with individual eggs having the appearance of a grain of rice with a gray to purplish color.
