The praying mantis follows a life cycle that exemplifies incomplete metamorphosis, or hemimetabolism. This developmental path involves three main stages: the egg, the nymph, and the adult, bypassing the pupal stage seen in creatures like butterflies. The mantis is a sophisticated ambush predator throughout its life. The entire life span, from hatching to death, typically lasts less than a year in temperate climates.
The Beginning: The Ootheca
The life of the praying mantis begins inside the ootheca, a specialized protective egg case. The female secretes a frothy substance, mixes it with fertilized eggs, and the mass quickly hardens into a durable, foam-like casing. This structure is deposited on stable surfaces, such as plant stems, twigs, or rocks.
The ootheca functions as a robust shield, insulating the hundreds of eggs inside from environmental threats like harsh weather, desiccation, and predators. In cold regions, the ootheca allows the eggs to overwinter, remaining dormant until warmer temperatures trigger the hatching process.
When conditions are right, tiny nymphs emerge en masse from the protective casing. These hatchlings are initially soft-bodied and must immediately begin to disperse to avoid being eaten by their siblings.
Growth and Transformation: The Nymph Stage
The newly emerged nymph closely resembles a miniature version of the adult. Nymphs are small and typically lack the fully developed wings that characterize the adult form. These young mantises are immediately active and voracious predators, using their raptorial forelegs to secure small live prey.
To accommodate their increasing size, nymphs must periodically shed their hard, inflexible outer skeleton in a process called molting. A mantis typically progresses through five to ten instars before reaching maturity. Before a molt, the mantis often stops eating and finds a secure location.
The mantis is particularly vulnerable immediately after shedding its exoskeleton, as the new cuticle is soft. The nymph stage usually lasts several months, during which the young mantis must continue to hunt and molt successfully. This growth phase continues until the final molt, which signals the transition to the reproductive stage.
Maturity and Reproduction: The Adult Stage
The final molt transforms the nymph into a sexually mature adult. This stage is primarily dedicated to reproduction, with females generally becoming larger than males.
Mating occurs during this final stage, often in the late summer or early autumn. Following successful copulation, the female focuses on producing the next generation. She lays her fertilized eggs into a new ootheca, linking the life cycle back to its beginning.
In temperate climates, the adult stage is relatively short, usually lasting only a few months. Once the female has deposited her eggs, the adults rarely survive the onset of cold weather. The adult mantis dies, often with the first hard frost, leaving the protected eggs within the ootheca to safely overwinter.