Praying mantises undergo a process of molting, which is how they grow and develop throughout their lives. This shedding of their outer layer allows them to increase in size and progress through various life stages. Molting is a necessary part of a mantis’s development, without which they could not reach their adult form.
The Molting Process
Praying mantises molt because their outer covering, called an exoskeleton, is rigid and does not expand. This hard, protective shell provides support and defense, but it restricts growth. To grow larger, the mantis must shed its old exoskeleton and form a new, bigger one. This process, known as ecdysis, is triggered by hormones.
Before molting, a mantis will typically stop eating and become less active. It will then seek a secure, elevated spot. The mantis begins to pump air and hemolymph (insect blood) into its body, which increases internal pressure and causes the old chitinous carapace to split, usually along its back. The mantis then extracts itself from the old skin. This shedding can take an hour or more.
Molting Through Life Stages
Molting occurs during the nymph stages of a praying mantis’s life cycle. After hatching, nymphs are called instars. They then undergo a series of molts, with each molt marking the progression to the next instar (L2, L3, and so on).
The number of molts a praying mantis experiences varies by species, but it generally ranges from five to ten times during its nymphal development. Females often have one or two more molts than males, which can lead to males maturing earlier. Once a praying mantis reaches its final molt, it becomes an adult and it will not molt again.
Life After the Molt
Immediately after molting, a praying mantis’s new exoskeleton is soft and pliable. The mantis remains suspended, often attached to its old skin, to allow the new exoskeleton to expand and begin hardening. This hardening process, called sclerotization, is essential for the mantis to regain its protective outer layer and takes time, typically around 24 hours for nymphs and sometimes up to four days for adults. During this period, the mantis expands its new, soft body by pumping hemolymph and air, which helps it increase in size.
The period directly following a molt is a time of considerable vulnerability for the mantis. Its soft body makes it susceptible to injury and predation. It is during this time that wings, if present, also expand and dry. The mantis will typically remain still and refrain from eating until its new exoskeleton has fully hardened, ensuring it is ready to resume its normal activities.