Locusts are a type of grasshopper distinguished by their ability to undergo a dramatic behavioral and physical transformation in response to population density. This change, from a solitary to a gregarious phase, allows them to form massive, destructive swarms. A locust’s total lifespan typically spans several months, ranging from 10 to 20 weeks from egg to adult death. This duration is highly variable and heavily influenced by environmental conditions.
The Locust Life Cycle: Stage Duration
The life of a locust proceeds through three distinct stages: egg, nymph, and adult, a process known as incomplete metamorphosis. The duration of each stage is closely tied to environmental factors, especially temperature and moisture. Under optimal conditions, the entire life cycle is completed relatively quickly, allowing for rapid population growth.
The initial stage begins when a female locust deposits her eggs in the soil, often in moist, sandy areas, forming a protective cluster called an egg pod. The incubation period for the eggs can be anywhere from 10 to 65 days, but under warm, favorable conditions, it is typically around two to four weeks. The eggs require sufficient moisture to absorb water and develop successfully before hatching.
Upon hatching, the young insect emerges as a nymph, or hopper, which is wingless and resembles a miniature adult. This stage involves growth through several molts, typically five to six instars, where the hopper sheds its rigid exoskeleton. The nymphal stage generally lasts between 30 to 60 days, during which the insect feeds voraciously to fuel its development.
After the final molt, the hopper transforms into a winged adult, or imago, which is capable of flight and reproduction. The adult lifespan can range from about two to five months, during which the locust reaches sexual maturity and mates. Mature gregarious females are known to lay multiple egg pods, contributing hundreds of offspring to the next generation before the end of their lives.
Factors That Modify Longevity
The total lifespan of a locust is flexible and significantly altered by external and internal factors. The most profound internal influence is phase polymorphism, the switch between the solitary and gregarious phases. Solitary locusts, which live at low population densities, often have a longer adult lifespan, sometimes approaching a year, as they face less stress and lower reproductive pressure.
In contrast, locusts in the gregarious, swarming phase prioritize rapid reproduction and migration. This high-energy lifestyle, involving intense feeding, constant movement, and the stress of high population density, tends to shorten the adult lifespan considerably, often reducing it to just a few months. The physiological demands of forming and maintaining a swarm accelerate the life cycle, sometimes leading to a total duration of just three to five months from egg to adult death.
Environmental conditions, particularly temperature and food availability, directly regulate the speed of development and survival. Higher temperatures generally accelerate the metabolic rate, shortening the time required for the egg and nymph stages. However, excessively high temperatures increase the risk of overheating and dehydration, which can truncate the potential lifespan, especially for nymphs and adults lacking shade.
Cooler temperatures, conversely, can significantly extend the duration of the nymphal stage, sometimes doubling the time needed to reach adulthood. The presence of ample green vegetation, typically following rainfall, provides the necessary moisture and food, enabling swift growth and development. When food or water is scarce, development can be slowed, and the longevity of all stages is negatively impacted by starvation or desiccation.