Praying mantises are fascinating predators in many temperate ecosystems. Adult mantises do not hibernate or enter a prolonged state of dormancy. Their survival strategy is tied to their life cycle, which utilizes a specialized, highly durable egg case to bridge the seasons. This mechanism ensures the species persists through the coldest months, even though the adults themselves perish.
The Fate of Adult Mantises
Adult praying mantises live on an annual cycle, emerging in late spring and reaching maturity by late summer or early autumn. Their lifespan is limited to one growing season, and the adult form is not adapted to endure freezing temperatures. The female’s final act is to lay her eggs, securing the next generation before the cold arrives.
As autumn deepens and temperatures consistently drop, the adult mantises die off naturally. This end-of-life process, known as senescence, is accelerated by the first hard frosts and the corresponding decline in available insect prey.
How Praying Mantises Survive Winter
The survival of the species relies on the ootheca, the specialized egg case. In the fall, the female mantis secretes a frothy material from glands in her abdomen, whipping it into a pale, foam-like mass around her fertilized eggs. This mass is then affixed to a sturdy surface, such as a twig, a plant stem, or a fence post.
Upon exposure to the air, the frothy material rapidly hardens into a dense, protective capsule. This hardened structure provides protection for the dozens or even hundreds of eggs housed within. The ootheca acts as an insulating barrier, safeguarding the developing embryos from desiccation, predation, and temperature fluctuations throughout the winter.
The eggs inside the ootheca enter diapause, a period of suspended development, triggered by cooling temperatures and short daylight hours. This strategy allows the embryos to remain dormant and protected from freezing until warmer conditions return. The durability of this capsule is the means by which the mantis lineage survives the cold season, pausing the life cycle until spring.
Springtime Emergence of Nymphs
Once winter recedes and conditions become favorable, the developmental clock for the eggs within the ootheca restarts. The eggs require rising ambient temperatures and sufficient humidity to break diapause and begin development. This emergence is timed to coincide with the availability of small insect prey, such as aphids and fruit flies.
When the moment arrives, tiny, wingless baby mantises, known as nymphs, execute a synchronous hatching, often emerging en masse from small exit points in the ootheca. They initially appear yellowish and hang from the egg case by silk-like threads before dropping to the ground and dispersing rapidly. The newly hatched nymphs are miniature, immediately predatory versions of the adults, and will begin to hunt and grow, starting the annual life cycle anew.