The Mormon cricket (Anabrus simplex) is a large, flightless insect native to the rangelands of Western North America. Despite its common name, it is a species of shield-backed katydid, distinguished by its thick body and long antennae. These insects are notorious for forming massive, cohesive bands that migrate across the landscape. This migratory behavior, where bands can travel up to a mile or more per day, often brings them into conflict with agriculture.
Overall Lifespan and Habitat
The active lifespan of the Mormon cricket, measured from the moment of hatching to natural death, typically spans five to seven months. This timeline includes the immature nymph stages and the final adult phase, occurring within a single calendar year. The species thrives across the semi-arid environments of the Western United States, including the Great Basin and the foothills of mountain ranges. This habitat is characterized by sagebrush and various forbs, which constitute a significant part of the cricket’s diet.
Developmental Stages
The life cycle begins with the egg stage, which accounts for the majority of the total time spent in a dormant state. Females lay eggs in the soil during the summer and fall, where they enter a period of arrested development known as diapause to survive the winter months. Hatching occurs the following spring, typically beginning when the soil temperature reaches approximately 40°F (4°C). In some populations, eggs may remain in the soil for an additional year or more before hatching, acting as a natural bet-hedging strategy against environmental unpredictability.
Once hatched, the young insects, called nymphs, develop and grow over a period of 60 to 90 days, depending on local temperatures and food availability. During this immature period, the nymphs undergo seven distinct growth stages, or instars, each separated by a molt. The nymphal stage is characterized by intense feeding and growth, where the insects are highly mobile and begin to form the large, damaging bands for which they are known. By the end of the nymphal period, the crickets have reached their maximum size and are ready to transition into their reproductive phase.
Adult Life and Duration
The adult phase begins in the early to mid-summer, following the final molt. Adult Mormon crickets survive for about two to three months, focusing their energy primarily on reproduction and migration. Mating commences quickly, typically within 10 to 14 days of reaching the adult stage. Males pass a large, nutrient-rich package called a spermatophore to the female, which serves as both a source of sperm and a significant food supplement.
This nutritional investment allows the female to produce a high number of eggs, with a single female capable of laying 85 to 180 eggs in the soil. The persistent, large-scale migrations continue in the adult stage, often covering long distances in search of new food sources and oviposition sites. The adult lifespan concludes as the season cools, with the population naturally terminating in the early fall due to the combined stresses of exhaustion, disease, and the onset of freezing temperatures.