What Is Molting?
Molting in insects is, by definition, the process of shedding and removing the exoskeleton of an arthropod. The exoskeleton is an external skeleton found in arthropods; where vertebrates like mammals and birds have an internal skeleton, insects, crustaceans and arachnids have a solid, outer skeleton known as the exoskeleton.
Why Do Mantis Need To Molt?
Praying mantis, and by extension all arthropods, molt to grow. The exoskeleton, while strong and protective, is rigid and inflexible. This inhibits your mantis from growing larger than the exoskeleton allows. Animals with exoskeletons are essentially trapped in their own skin, so in order to grow, they need to break out and slowly form a larger one.
A secondary reason for molting which you see in longer-lived animals like tarantulas, is to renew their damaged exoskeleton. In other words, some athropods molt to heal injuries.
A Madagascan marbled mantis.
The exoskeleton after moulting.
What Are The Signs My Mantis Is Going To Molt?
There are several indicative signs of an approaching moult in mantises. Refusal of food, lethargy, erratic vibration-like movements, inflation of the abdomen, elongated and extended legs, open raptorial arms, and large, swollen wing buds in sub-adult mantids.
This is a lot of info if you’re new, so we will break it down.
Most new mantis keepers panic when their first mantis stops eating. Thankfully, this is a perfectly normal reaction to your mantis being in pre-moult. This fasting phase typiclaly lasts just a few days and is generally of no concern as praying mantis will happily go weeks without food.
The most telltale sign of an approaching molt is in the inflation of the abdomen, especially if they have also been refusing food. Praying mantis absorb a large amount of air in their abdomen before finally molting.
Additionally, mantis in pre-molt will hang from the top of their enclosure, however this is typical behaviour that can be difficult to differentiate from how they normally behave. Other signs worth noting include slightly parted raptorial front arms and elongated, extended body & legs as they stretch down from the top of the enclosure. It’s also common to see frequent erratic movements & vibrations that last for a few seconds at a time.
My Mantis Is Molting, What Should I Do?
You should almost never intervene in the molting process. After your mantis has broken free of its exoskeleton, it will hang, suspended in the air, attached only to the previous skin by its lower abdomen. While it may look stuck, this hanging phase is called hardening.
Hardening is the process of “fortifying” the new exoskeleton after removing the old one. Internal secretions are released which harden this new exoskeleton into a defensive exterior like the last. Between the moulting and hardening phase, your mantis undergoes a short burst of growth while the new exoskeleton is soft enough to allow it.
This means that your mantis is extremely soft and vulnerable and should not be handled or fed. We recommend leaving a mantis around 48 hours before handling or feeding post-molt. A praying mantis will not accept food until it has hardened, so feeding is a good way to gauge whether they are strong enough to handle. To summarise, do not handle your pet again until they happily accept and eat prey.
The Instar System
Instars refer to the developmental stages of an arthropod. Instars are measured by the number of moults, which is specific to the animal and species. Most praying mantis species have around 6-10 total moults, depending on species & sex.
A “newborn” mantis nymph is classed as L1. After its first moult, it becomes L2, after its second, L3, and so on until adulthood. Smaller mantis species & male mantis typically have fewer total moults until adulthood. For example, female orchid mantids, Hymenopus coronatus, have 9 total instars, where male orchid mantis have only 7.
Most mantis nymphs are sold at L2.
Wings, Wing-Buds, And Adulthood
A praying mantis will not moult again after reaching adulthood. A mantis becomes an adult when they have grown wings during their final molt.
Sub-adult praying mantis (mantis one molt away from adulthood) have wing buds, small, bud-like appendages located between the thorax and abdomen, as shown on this P. aeruginosa nymph.
Praying mantis grow wings as adults. Can they fly? That depends. Female mantids usually can’t fly at all due to their weight, and any attempt to do so is comparable only to a flighted jump. Males, on the other hand, usually can fly.
The process of gaining wings in mantises is almost identical to that of a butterfly. After your mantis completes its final molt, its tiny crinkly wings are revealed. Not yet inflated, the mantis then turns to the sky, allowing gravity to help pump fluid into the wings.
A Madagascan marbled mantis nymph.
P. aeruginosa mature adult female with wings.
What Are Mismolts?
Mismolts are complications in moulting that result in physical deformities. Preventing mismolts is, unarguably the most important aspect of mantis care as mismolting may be responsible for the majority of deaths in arthropods.
Common symptoms of mismolts include bent body parts, a curvature of the entire body or thorax, crinkled or splayed wings and missing limbs.
This picture shows an example of mismolt deformities. This mantis has deformed, bent legs and crinkled wings. Sometimes, despite all effort, mismolts do just happen. Following the correct care, however, will significantly reduce that chance of molting issues in your mantis.
How Do You Prevent Mismolts? Humidity, Housing, Hydration.
Mismoults in praying mantis are typically due incorrect humidity levels, dehydration, insufficient space, and lack of easily navigatable surfaces.
You’ve probably already heard of the importance of humidity. Humidity in the environment assists in softening the exoskeleton of your mantis, which is why it’s necessary to follow the required RH (relative humidity) level for your species.
Praying mantis are situated all over the world. The orchid mantis hails from the humid jungles of south Asia, and the ghost mantis from arid Africa. These two species have vastly different humidity requirements, and so it’s vital to follow as instructed on your species’s care sheet.
Hydration is key in driving the molting process internally, as removal of the exoskeleton is catalysed by bodily secretions. If you’ve read our care sheet, you’ll know to mist your mantis daily. This increases the RH level of your mantises enclosure, and allows them a daily drink to stay hydrated.
The most important detail of your mantids enclosure is undoubtedly its size. A praying mantis enclosure needs to be at least 3x as tall as the insect’s total body length.
During a molt, a praying mantis must extend from the top of its enclosure downward as it wriggles free of its exoskeleton. Without enough space for this to safely happen, your mantis will harden in an unhealthy position.
Let’s now touch on a point that is often overlooked, especially by beginners.
Praying mantis cannot efficiently grip and navigate glass, plastic, or smooth surfaces. While it’s possible for them to walk on glass, it’s not at all easy. This is why it’s ever so important to decorate any enclosure with natural decor such as bark, sticks, live plants and substrate. This enables your mantis to happily explore its enclosure, but most importantly, it ensures your mantis will not fall mid-molt.
For the exact same reason, you need to have some kind of mesh on the top your enclosure.
If you’re using a mesh insect enclosure, brilliant, however this may struggle to keep in humidity. Store-bought glass exotic pet enclosures typically come with a mesh lid, although they can be expensive. If you’re creating your own enclosure, it’s easy enough to add a mesh to the lid and sides. We recommend enclosures with a mesh roof and single mesh wall panel for most species, to strike a good balance between good navigation, ventilation, and humidity.
To learn out more about building and decorating enclosures, and how to create an enclosure for a high-humidity species, make sure to read our article below.
Read: How To Make A Praying Mantis Enclosure.
About Exoskeleton Wear & Tear
So, we know that mantids regularly moult as nymphs. But, in old age, the exoskeleton deals with natural wear & tear since it’s no longer being consistently renewed. This leads to a natural degeneration of the body. Body parts can break off or seize up, causing the mantis to rely on other damaged body parts to move, exacerbating the problem. This is a natural symptom of old age, and the best way to avoid it is by ensuring you are handling your mantis incredibly gently or even not at all when the first signs of degeneration start.
Why Is My Praying Mantis Not Molting?
So, we know that several times throughout their lifetime. The time between moults, however, is never the same. As mantids get older, the time until the next molt increases exponentially until adulthood. Keeping a mantis warm or cool, well-fed or under-fed influences their metabolism, and thus the time it takes until the next moult.
1. You're Not Feeding Often Enough
The amount of food your mantis is getting will affect their metabolism. Praying mantis fed less will have a longer interval between molts, and mantis fed more will have shorter intervals. This also affects their entire lifespan, you can lengthen it or slow it down depending on their feeding schedule.
While we have an entire guide on feeding your mantis, we’ll quickly note that it’s important to feed your mantis based on the size of their abdomen. A plump abdomen shows they are full, conversely a thin abdomen shows they are hungry.
2. The Temperature Is Too Low
Temperature, as well as hunger, has a direct affect on the metabolism of your mantis. All mantis species are different, and they all have different temperature requirements. It’s important to do research into the species you own to ensure you’re keeping them at the correct temperature. Beginner species, like the ghost mantis, giant Asian mantis are typically content when kept at around room temperature, where advanced species will need it a little warmer.
4. Your Mantis Is Already Fully Matured
We often come across posts on mantis forums of people congratulating their nymphs on reaching adulthood. To recap, you can know with complete certainty that your mantis is an adult as it will have wings. Mantis stop molting completely after becoming adults.
Giant Asian mantis nymph
Mature giant Asian mantis male.
Fully developed wings.