What is a Mormon cricket?

Mormon crickets (Anabrus simplex) are large, flightless shield-back katydids (family Tettigoniidae) — not true crickets. Adults are 3–7 cm long, brown to black or reddish, with a distinctive saddle-shaped pronotum (shield) covering the thorax. Females have a long, curved ovipositor. They are named for the 1848 Miracle of the Gulls in Utah, where California gulls reportedly saved Mormon settlers' crops from a Mormon cricket infestation. They are found throughout the western United States including northern and central Arizona.

Do Mormon crickets swarm in Arizona?

Yes — Mormon crickets are famous for forming massive migratory bands of thousands to millions of individuals that march across the landscape consuming virtually all vegetation in their path. These bands can be 1–2 miles wide and travel 1–2 km per day. Swarming is triggered by population density, drought stress, and protein/salt deficiency — the crickets are actually cannibalistic, and marching keeps them moving away from being eaten by the crickets behind them. Major outbreaks occur in northern Arizona, particularly in Coconino and Navajo counties.

Are Mormon crickets dangerous to humans?

Mormon crickets are not dangerous to humans — they do not bite aggressively, are not venomous, and do not transmit disease. They are a significant agricultural pest, capable of destroying rangeland, crops, and gardens. Dead crickets on roads can create hazardous driving conditions. They are also a nuisance when they enter homes in large numbers.

What do Mormon crickets eat?

Mormon crickets are polyphagous — they eat almost any plant material including grasses, forbs, shrubs, and crops. They also eat dead insects and carrion, and will cannibalize injured or dead Mormon crickets (which is a key driver of their swarming behavior). During outbreaks, bands can cause significant damage to rangeland, alfalfa, wheat, and vegetable crops.

How are Mormon cricket outbreaks controlled?

Large-scale Mormon cricket outbreaks are managed by USDA APHIS using aerial application of carbaryl bait (Sevin bait) or Nosema locustae (a naturally occurring microsporidian pathogen). For property-level protection, perimeter insecticide barriers (bifenthrin, permethrin) can reduce invasion. Natural predators including birds (especially ravens and gulls), coyotes, and ground beetles help suppress populations. Outbreaks are cyclical and typically subside after 2–5 years.

What is a Mormon cricket?

Mormon crickets (Anabrus simplex) are large, flightless shield-back katydids (family Tettigoniidae) — not true crickets. Adults are 3–7 cm long, brown to black or reddish, with a distinctive saddle-shaped pronotum (shield) covering the thorax. Females have a long, curved ovipositor. They are named for the 1848 Miracle of the Gulls in Utah, where California gulls reportedly saved Mormon settlers' crops from a Mormon cricket infestation. They are found throughout the western United States including northern and central Arizona.

Do Mormon crickets swarm in Arizona?

Yes — Mormon crickets are famous for forming massive migratory bands of thousands to millions of individuals that march across the landscape consuming virtually all vegetation in their path. These bands can be 1–2 miles wide and travel 1–2 km per day. Swarming is triggered by population density, drought stress, and protein/salt deficiency — the crickets are actually cannibalistic, and marching keeps them moving away from being eaten by the crickets behind them. Major outbreaks occur in northern Arizona, particularly in Coconino and Navajo counties.

Are Mormon crickets dangerous to humans?

Mormon crickets are not dangerous to humans — they do not bite aggressively, are not venomous, and do not transmit disease. They are a significant agricultural pest, capable of destroying rangeland, crops, and gardens. Dead crickets on roads can create hazardous driving conditions. They are also a nuisance when they enter homes in large numbers.

What do Mormon crickets eat?

Mormon crickets are polyphagous — they eat almost any plant material including grasses, forbs, shrubs, and crops. They also eat dead insects and carrion, and will cannibalize injured or dead Mormon crickets (which is a key driver of their swarming behavior). During outbreaks, bands can cause significant damage to rangeland, alfalfa, wheat, and vegetable crops.

How are Mormon cricket outbreaks controlled?

Large-scale Mormon cricket outbreaks are managed by USDA APHIS using aerial application of carbaryl bait (Sevin bait) or Nosema locustae (a naturally occurring microsporidian pathogen). For property-level protection, perimeter insecticide barriers (bifenthrin, permethrin) can reduce invasion. Natural predators including birds (especially ravens and gulls), coyotes, and ground beetles help suppress populations. Outbreaks are cyclical and typically subside after 2–5 years.

Mormon Crickets in Arizona — The Swarming Shield-Back Katydid That Devours Everything

Back to Blog11 min readNorthern Arizona

Agricultural Pest

Mormon cricket outbreaks can strip rangeland and crops across miles of Arizona. Bands of millions march 1–2 km per day consuming virtually all vegetation.

Mormon crickets are not true crickets — they are shield-back katydids that form massive migratory bands capable of stripping vegetation across miles of Arizona rangeland. Here's what you need to know.

The Mormon cricket, Anabrus simplex, is a shield-back katydid in the family Tettigoniidae—not a true cricket. Its name recalls Utah’s 1848 “Miracle of the Gulls,” when California gulls reportedly consumed insects threatening Mormon settlers’ crops. Adults are flightless and range from brown or black to reddish, with a saddle-shaped pronotum over the thorax and a long female ovipositor.

Mormon cricket quick ID

Size

3–7 cm

Type

Shield-back Katydid

Outbreak

Millions/band

Counties

Coconino, Navajo

Why bands march

At high density, food stress and shortages of protein or salt can shift Mormon crickets from dispersed living to coordinated movement. Cannibalism is an important engine of migration: individuals at the rear risk being eaten, while those ahead keep moving. The resulting bands may be thousands to millions strong, travel one to two kilometers daily, and consume grasses, forbs, shrubs, and crops as they pass.

Arizona outbreak impacts

Northern Arizona—especially Coconino and Navajo counties—can experience outbreak conditions on rangeland and around alfalfa or wheat. Besides vegetation loss, dead crickets can make roads slick, creating a vehicle hazard. Outbreaks tend to be cyclical, often subsiding over roughly two to five years as weather, disease, predators, and food conditions change.

Control at landscape and property scale

USDA APHIS programs may use carbaryl bait or the microsporidian Nosema locustae on large infestations. Ravens, gulls, coyotes, and other predators also consume crickets. For homes and businesses within the Pest Control Bros service area, a targeted bifenthrin perimeter may reduce local entry pressure; keep vegetation and debris away from the structure and call promptly when a moving band approaches.