Praying mantises are distinctive insects known for their predatory habits. Their triangular heads, large compound eyes, and powerful, spiky forelegs, held in an upright position, give them a unique “praying” stance. These ambush predators blend into surroundings like gardens, meadows, and forests across temperate and tropical regions worldwide.
The Female’s Fate After Egg Laying
A common misconception suggests that female praying mantises die immediately after laying their eggs. While many do perish shortly thereafter, this is not a direct consequence of the act itself. Creating the ootheca, the protective egg case, is an energy-intensive process, sometimes representing 30% to 50% of her total biomass.
The female may lay multiple oothecae, weeks apart, profoundly draining her energy reserves. While some females might survive for a few weeks or even months after their final egg-laying, especially in warmer climates, their eventual demise is often linked to the culmination of these biological demands and environmental pressures.
Factors Influencing Post-Reproductive Survival
The death of a female praying mantis after egg laying is influenced by environmental and biological factors. A primary cause of death for mantises in temperate climates is cold weather, as they cannot survive freezing temperatures. The first hard frost often marks the end of their lives.
Beyond temperature, the energy expenditure to produce the ootheca leaves the female weakened. This resource depletion reduces her ability to hunt, making her susceptible to starvation. A weakened state increases her vulnerability to predators like birds, spiders, and other insects. Sexual cannibalism, where the female consumes the male during or after mating, can provide nutrients for egg production, but it does not prevent her eventual decline.
The Mantis Life Cycle
The praying mantis undergoes incomplete metamorphosis, progressing through three main stages: egg, nymph, and adult. In late summer or early fall, the female deposits her eggs within a specialized, protective structure known as an ootheca. This foam-like case hardens around the eggs and is attached to a plant stem, providing insulation and protection throughout the winter months.
As spring arrives, nymphs hatch from the ootheca, emerging as miniature versions of the adult mantis. These nymphs grow by undergoing a series of molts, shedding their exoskeletons to increase in size. They reach their adult stage by late summer. Adult praying mantises have a lifespan of about six months to one year in the wild, meaning their reproductive period and subsequent death align with the end of their annual life cycle and the changing seasons.