Anabrus simplex

The Anabrus simplex, more commonly known as the Mormon cricket, is a flightless insect native to western North America. Despite its name, it’s not a cricket but belongs to the katydid family, Tettigoniidae. This large, herbivorous insect has captured attention for its swarming behavior, historical interactions with human settlements, and ecological significance.

Physical Description and Habitat

Mormon crickets are relatively large, measuring up to 2 inches (5 cm) in length. They lack wings, making them flightless, and have elongated hind legs adapted for powerful jumping. Their bodies are typically brown or tan, with females often exhibiting green coloration. The distinguishing feature of this species is the large, shield-like plate covering their thorax, earning them the nickname “shield-backed katydid.”

These insects primarily inhabit rangelands dominated by sagebrush and forbs in the western United States and southern Canada. They can be found in various elevations, from valleys to mountain slopes, preferring dry and open environments.

Lifecycle and Swarming Behavior

Mormon crickets have a unique lifecycle that includes both solitary and swarming phases. Solitary individuals typically live for about a year, going through incomplete metamorphosis with five nymphal stages before reaching adulthood. During this solitary phase, they feed on various plants and grasses, contributing to the ecosystem’s herbivore community.

However, under certain environmental conditions, such as abundant rainfall followed by drought, Mormon crickets can enter a swarming phase. This dramatic shift involves dramatic population increases and the formation of dense, mobile bands containing millions of individuals. These bands can travel impressive distances, sometimes covering up to 2 kilometers (1.2 miles) per day, in search of food.

During this phase, their behavior changes significantly. They become highly social, feeding voraciously on almost any vegetation in their path, including crops and even small animals. This can cause significant agricultural damage and ecological disruption, earning them a reputation as pests.

Historical Significance and the “Miracle of the Gulls”

Mormon cricket is intertwined with the history of the early Mormon settlers in Utah. In 1848, just as their crops were nearing maturity after a challenging journey westward, a massive swarm of Mormon crickets descended upon the Salt Lake Valley, threatening to destroy their livelihood. According to their accounts, they prayed for deliverance, and a flock of gulls arrived, devouring the crickets and saving their crops. This event, known as the “Miracle of the Gulls,” became a significant part of Mormon folklore and solidified the association between these insects and the Mormon community.

Ecological Significance and Conservation Status

Despite their potential for pest outbreaks, Mormon crickets play an important role in the western North American ecosystem. They contribute to nutrient cycling by decomposing organic matter and serve as prey for various birds, reptiles, and other animals. The population dynamics of these insects are complex and influenced by various factors, including weather patterns, predators, and habitat availability.

While they are not currently considered an endangered species, their populations can fluctuate greatly, and human activities like habitat modification and pesticide use can impact their long-term sustainability. Conservation efforts focus on understanding their population dynamics, managing potential outbreaks sustainably, and preserving their essential role in the ecological balance.


The Anabrus simplex is a fascinating insect with a unique combination of biological and historical significance. Their swarming behavior, ecological roles, and historical encounters with humans make them a captivating subject for study and appreciation. Understanding and respecting these remarkable creatures is crucial for maintaining the ecological balance of western North American ecosystems and appreciating the intricate relationships between humans and the natural world.