Mormon Cricket

Despite its common name, the Mormon cricket is not a true cricket but a large, wingless shieldback katydid native to the sagebrush and bunchgrass rangelands of the American West. It earned its name from early Mormon settlers in Utah who battled swarms of the insect devastating their crops in the 1840s, an event later commemorated by the "seagull miracle" story. The species is best known for its irregular, large-scale population outbreaks, during which millions of individuals form dense marching bands that can travel considerable distances over open ground.

Adults are stout-bodied and heavy, with a domed, shield-like pronotum covering the thorax that gives the shieldback katydid group its name. Color varies widely between populations and even individuals, ranging from black and brown to deep red, purple, or green, sometimes with a mottled or striped pattern. Because the wings are reduced to small pads, Mormon crickets cannot fly and instead rely entirely on walking and hopping to disperse, which is part of what makes their coordinated mass migrations so visually striking.

Ecologically, Mormon crickets are omnivorous generalists, feeding on forbs, grasses, shrubs, and occasionally other insects, including their own kind. Their periodic outbreaks can strip vegetation over large areas, but in non-outbreak years they are simply an inconspicuous part of the shrub-steppe insect community and serve as a food source for birds and small mammals.

• Large, robust body, roughly 2-3 in (5-7.5 cm) long, with a noticeably domed, shield-shaped pronotum
• Wings reduced to small stubs; flightless and ground-bound
• Coloration highly variable: black, brown, reddish, purplish, or greenish, sometimes mottled or striped
• Females have a long, curved, sword-like ovipositor extending from the rear
• Thick hind legs adapted for jumping and walking rather than sustained flight
• Distinguished from true crickets by the shield-like pronotum and from grasshoppers by very long, thread-like antennae

Mormon crickets inhabit arid and semi-arid rangeland across the Intermountain West and Great Basin, including Utah, Nevada, Idaho, Wyoming, Montana, and parts of neighboring states. They favor sagebrush steppe, bunchgrass prairie, and open rangeland with a mix of forbs and shrubs. Adults are active from late spring through summer, with outbreak bands most conspicuous in June and July as they march across roads, hillsides, and pastures searching for food and breeding sites.

Mormon crickets are diurnal and highly gregarious during outbreak years, forming dense migratory bands that move in a coordinated direction across the landscape, sometimes covering a mile or more in a day. This mass movement is thought to be driven partly by nutrient-seeking behavior and partly by predator avoidance, since individuals lagging behind a moving band risk being eaten by their own crowded neighbors. They are omnivorous, grazing on a wide variety of range plants, seeds, and occasionally scavenging or preying on other insects. Outside of outbreak phases, populations are solitary and much less noticeable, blending into the shrub-steppe environment. Birds, rodents, and other predators feed heavily on Mormon crickets, making them an important seasonal food source in rangeland food webs.

Mormon crickets undergo incomplete metamorphosis with three life stages: egg, nymph, and adult. Females use their long ovipositor to deposit eggs in the soil in late summer, and the eggs overwinter, sometimes for more than one year, before hatching in spring. Nymphs emerge wingless and gradually grow through several molts over the course of the summer, resembling miniature, paler versions of the adults. There is a single generation per year in most populations, with adults dying off by late summer after breeding and egg-laying is complete.